Chapter 3

Direct Physical Evidence

Roy Craig

0. Introduction
1. Markings Allegedly Made By UFOs
2. Material Allegedly Deposited by UFOs
3. Parts of UFOs, or UFO Equipment
4. Conclusion
BACK to Contents


Several types of physical effects have been presented as evidence that an object of unusual nature had been present at a given location. Such effects consist of:

  1. markings on ground, vegetation, or objects with which an UFO, as something from an UFO, reportedly made direct or indirect physical contact;

  2. material residue allegedly deposited from or by an UPO and

  3. articles or portions of articles manufactured by intelligent beings, but reportedly not produced by known cultures.

A fourth known conceivable type of physical evidence, consisting of a non-earthly or captured "flying saucer," would be most impressive as evidence. The existence of this type of evidence has been suggested by some reporters, such as Moseley (1967), who reported the claim that a captured flying saucer was held at a military base in Ohio, and Allen (1959), who presented a photograph of a tiny humanoid creature and four adult Earth residents, claiming that the creature was a crewman of a saucer which crashed near Mexico City in 1950. During the course of this study, however, no indication was found that this fourth type of evidence has ever existed.


1. Markings Allegedly Made By UFOs

Claims of evidence of the first type are common. UFO reports contain numerous descriptions, often with supporting photographs of saucer "nests" -- areas where soil, grass, cattails, or other vegetation had been flattened, burned, broken off, or blown away, allegedly by an UFO that landed or hovered there. The Lorenzens (1967) also have described six case; in which sets of circular or wedge-shape depressions


were allegedly made by the landing legs of unidentified vehicles. A number of other cases of the landing-gear imprint type have been reported, including incidents at Presque Isle State Park, Pa., 31 July 1966; South Hill, Va., 23 April 1967; and Tucson, Ariz., 9 October 1967. These three cases were examined and analyzed by Project Blue Book. Hall (1964) and others have listed other cases in which ground impressions are claimed as evidence that unknown physical objects had been present. Hall's listing also includes a half dozen "nest" reports, and a 13-ft. ring imprint of a general type earlier reported in a case described by Maney and Hall (1961).

Reports of ring imprints are not uncommon. Four cases, involving ring imprints generally about 30 ft. in diameter and 6 - 12 in. wide were reported in August and September, 1967, in three different Canadian provinces. In Camrose, Alberta six different rings were reported. Photographs of the Camrose rings were received by this project for evaluation.

Claims of the saucer nest type of evidence were made in a few of the current cases investigated by the field teams (e. g. Cases 22, 25, 38). In some cases, the "nest" seemed imaginary. In other cases, the reality of an imprint, of a type which conceivably could have been made by a large saucer or by a being from a saucer, was evident (as in Case 22 ). However, in all such cases, it was impossible to establish as factual the claims that the imprints actually were made by an extraordinary object or being.

If the evidence displayed could have been the result of human or animal activity, or lightning or other natural events, the probability that it was so caused is much greater, in absence of independent evidence to the contrary, than the probability of its creation by an extraterrestrial vehicle or being: therefore, the burden of proof must lie with the person claiming a strange origin.


The independent evidence most frequently claimed is presence of unusual radioactivity at the site. In cases where such claims were checked by our field teams, ( 32 , 42) the claim was found to be untrue. In one case C 22 ), radioactive material was found to be present by Canadian investigators and in other cases, (e. g. Fisherville, Va., 12-21-64) which could no longer be checked, testimony by persons other than the UFO observer supported a claim that the site was found to be radioactive. In such cases, however, if radioactive material actually were present, the possibility that it was placed there by humans cannot be ignored. If humans are known to have visited the site before official confirmation of presence of radioactive material has been made, and the material found is either a naturally occurring radioactive mineral or a commercially available luminous paint, the presence of this material serves to weaken any claim of strange origin of the markings.

The existence of an imprint of odd shape or a circular area of crushed vegetation often can be established. Its mere existence does not prove, however, that the marking was made by a strange being or vehicle. Demonstration of a connection between such markings and strange objects has thus far not been accomplished. Attempts to establish such connection must still depend upon personal testimony. Generally, personal testimony includes the reported sighting of an UFO in the area of the discovered imprints or nest. Quite frequently, however, UFO origin of the markings is assumed, even though no UFO was seen in the area near the time the markings must have been made. This was true of the Camrose rings, whose appearance did not differ markedly from tracks left by wheels of farm vehicles. In case 38 "nests" were reportedly discovered in the forest just after the field team investigated a multitude of UFO reports in the region. The project sent photographs of these circular patches of forest damage to Dr. Carl E. Ostrom, Director of Timber Management Research, U. S.


Forest Service, for comment. Dr. Ostrom listed four natural causes of such patches of forest damage. He indicated that members of the Forest Service had observed similar damage in other regions under ecological conditions similar to those in the area in which these "saucer nests" were reported. Although UFOs had been reported in the general region, there again was no direct connection between them and the patches of timber damage, the existence of which could be accounted for by quite earthly processes.

Generally there are no physical tests which can be applied to a claimed saucer landing site to prove the origin of the imprints. Occasionally, the degree of compaction of soil by UFO "landing legs" is presented as evidence that the force was extraordinary. However, if the compaction could have been achieved by a human with a sledge hammer, for example, compaction measurements are of little significance, since they do not yield information regarding the cause of compaction. Chemical tests of soil can sometimes be used to disprove a claim, but are not likely to support a claim of strange origin of markings, since there is no obvious reason to expect chemical alteration. For example, samples of soil from a golf course at Port Townsend, Wash, were submitted to this project for analysis (Case 1406P, 1074T, project files). One sample was taken from a burned area where an UFO, reportedly observed earlier by several youngsters, was assumed to have touched down. Comparison samples from unaffected areas nearby were also studied. Gas chromatography showed the existence of hydrocarbon residues in the sample from the burned area, indicating that gasoline or other hydrocarbon had been used to make this particular "saucer nest." An empty lighter fluid can was found in the area a few hundred yards away.


2. Material Allegedly Deposited by UFOs

An elusive material, called "angel hair" in UFO publications, is sometimes reported to have been deposited by UFOs. Seventeen cases involving "angel hair" were listed by Maney and Hall (1961) for the


period 1952 through 1955. In fourteen there was an associated sighting reported of an UFO. The "angel hair" is described as a fibrous material which falls in large quantities, but is unstable and disintegrates and vanishes soon after falling. It has also been described as filaments resembling spider webs, floating down to earth, hanging from telephone wires and tree branches and forming candy-floss-like streamers. These streamers, which sometimes are reported to cover areas as large as 0.25 sq. mi., also are reported to vanish on touch, burn like cellophane when ignited, and sublime and disappear while under observation. A somewhat similar evanescent residue, described as a luminous haze or a misty, smokelike deposit, was reported in three cases discussed by the Lorenzens (1967), and "angel hair" cases are also described by Michel (1958), who suggested that the material be collected and preserved at low temperature for crystal structure study by X-ray diffraction. Hall (1964) has stated that many deposits of "angel's hair" have been nothing but cob-webs spun by ballooning spiders. On at least one occasion, he wrote, small spiders have actually been found in the material. In other cases, the composition or origin of the "angels hair" is uncertain. During the course of this study, one sample of dry white powder was submitted to the project for analysis. It had been collected from beneath the eaves of a house over which "angel hair" was reported to have settled, leaving a sticky deposit. (Project files 1406P, 1074T). Since the major cationic component of this powder was titanium, it was concluded that the powder was the residue of a commonly used house paint containing a titanium oxide pigment. Few recent UFO reports have involved material of the "angel hair" type.

A second type of material often is assumed, because of the circumstances of its appearance, to have been dumped by UFOs. The material is commonly referred to as "space grass" and has appeared unexpectedly


in fields and yards after falling from the sky. Generally, no sighting of identified or unidentified objects is associated with the fall. The material is composed of metallic threads of lengths varying from a fraction of an inch to a foot or more, generally with many threads intertwined into a loose mass. Typical material of this type is described by Keel (1967), who suggests that UFOs are using the earth as a kind of garbage dump. Actually, "space grass" is aluminum "chaff" of the various sizes and types used by military aircraft to confuse tracking radar (see Section VI, Chapter 5).

Samples of material sent to the project for analysis because of their assumed UFO association were most commonly "space grass." The first sample was received from observers of two "space ships" reported over Manhattan Beach, Calif., on 5 February 1957. The material appeared 24 hr. after the sighting and was reported to have been radioactive when found. It was not radioactive when received. Analysis demonstrated it to be 1145 alloy bard aluminum foil chaff dipoles with both a slip and a stripe coating applied to the surface of the foil. Since the slip coating was color coded red, it could be identified as a product of the Foil Division of Revere Copper and Brass Incorporated, Brooklyn, N. Y. The company identified the chaff as its product. This chaff could have been dropped by aircraft. It also could have been carried aloft by sounding rockets or balloons, and released at high altitudes for radar tracking. It is certain, however, that this sample of "space grass," like other such samples submitted to the project for analysis, had a quite earthly origin, and was not deposited by vehicles of extra-terrestrial origin.


3. Parts of UFOs, or UFO Equipment

Frank Edwards (1966) discusses three cases in which an UFO or part of an UFO is claimed to have been recovered:

  1. a flying disc reported to have crashed on Spitzbergen Island in 1952 and to have been recovered, badly damaged but intact, by the Norwegian Air Force;


  1. a 1 lb. fragment from a 2 ft. diameter glowing disk which was reportedly intercepted over Washington, D. C., in 1952; and

  2. a 3,000 lb. mass of "strange metal" found about 1 July 1960, in the St. Lawrence River in Quebec, and considered by a Canadian UFO investigator to be possibly a portion of a very large interstellar device which came into this solar system at an unknown time in the past.

Efforts have been made to determine to what degree any of these claims might be factual. In the Spitzbergen case, Mr. Finn Lied, Director, Norwegian Defense Research Establishment, replied that the only articles he knew of having been recovered in Norway have been traced back to rocket and satellite hardware. Mr. Tage Eriksson, of the Research Institute of National Defense, Sweden, replied that neither the Swedish Air Force nor the Research Institute of National Defense has at any time taken part in an investigation of a crashed UFO in Spitzbergen or elsewhere. A U. S. Air Intelligence Information Report, dated 12 September 1952, revealed that the Norwegian government knew nothing of such an object. The story apparently was the work of a West German reporter. It first appeared in the German newspaper "Berliner Volksblatt" for 9 July 1952. The original newspaper report stated definitely that the silver discus-like body was 48.88 m. in diameter and made of an unknown metal compound; its meters and instruments had Russian symbols, and it appeared to have a range of some 30,000 km. Significantly, the aspects of this first report implying that the vehicle was of Russian origin have been selectively neglected by subsequent writers, particularly those who urge that the claimed wreckage is extra-terrestrial in origin. It seems well established that this story has no basis in fact.

Representatives of Air Force Project Blue Book claimed no knowledge of the disc fragment discussed by Edwards, who claimed the successful


search for this fragment was confirmed by Lt. Cdr. Frank Thompson of the U.S. Navy. The fragment, said to have been dislodged by gunfire from a Navy jet, reportedly fell to the ground, where it was found, still glowing, an hour later by U.S. military ground search crews. Reports of UFO events over Washington, D. C., in 1952 contain no reference to such a gunfire incident. If such a fragment did exist and was classified "Secret" as was claimed, its existence and whereabouts would not necessarily be revealed to this project. A request for official confirmation that the claimed fragment did or did not exist and does or does not exist was forwarded to U.S. Air Force headquarters. A reply was received from J. W. Clinton, by direction of the Chief of Information, Department of the Navy. Mr. Clinton indicated that a thorough search of all Navy records available failed to reveal any account of a Navy jet fighter's encounter with an UFO in July 1952 or at any other time. Perhaps more significant, however, were the facts that Navy records of the year 1952 carried only one Frank Thompson, an individual who had retired from active duty several years before 1952 with the rank of lieutenant, not lieutenant commander. Navy fighters based near Washington were armed only for firing practice conducted far out at sea over a restricted firing area. Navy aircraft armed with live ammunition, Mr. Clinton pointed out, would have been usurping an Air Force function if they had been present over Washington, D. C., as interceptors. Mr. Clinton concluded: "The incident is not beyond the realm of possibility, but due to the nature of the Navy's jet operations about the Washington, D. C. area at the time, it was very highly unlikely."

The 3,000 lb. mass of metallic material from the St. Lawrence River was the subject of several communications received by this project. Among these was a letter from Mrs. Carol Halford-Watkins, Secretary of the Ottawa New Sciences Club (Project file l326-P). The Club now has custody


of the specimen. The Club does not claim that the piece of metal is, in fact, part of a spaceship; however, its members do not reject this possibility. Mrs. Halford-Watkins generously offered samples of the material for analysis and provided photographs of the object and a description of details of the find and analyses of the material. The Canadian Arsenals Research and Development Establishment (CARDE) had examined the non-homogeneous material, and described it as high-manganese austenitic steel. GARDE personnel considered the material the normal product of a foundry, consisting of slag with semi-molten scrap imbedded in it. The object was not believed to have fallen in the location where it was found, which is near Quebec City, in a channel of the St. Lawrence River which carries water only at high tide, for there was no crater nor splattered material in the vicinity.

A Quebec newspaper had reported that a fiery object fell out of the sky with an accompanying sonic boom rocking the area, prior to discovery of the massive metal in the river. Members of Ottawa New Sciences Club who investigated, however, were unable to find anyone in the area who had actually heard or seen the object fall. Since no connection could be seen between the existence of this metal or slag and the UFO question, no further analysis of the material was undertaken by the project. This writer examined the metallic mass at Ottawa and agreed with the CARDE conclusion that it was ordinary foundry waste.

Examination of claimed evidence of any of the three general types revealed a tendency of some persons to attribute to UFOs any track material, or artifact which seemed unusual and strange, even when there had been no sighting of an UFO in the vicinity. The 3,000 lb. metallic mass is one example. Another example was a ground depression and connecting system of crooked, thread-like tunnels found near Marliens, France, on 9 May 1967, and reported in The Flying Saucer Review (1967). The radar chaff "space grass" described above also illustrates this tendency. Metal spheres, a foot or two in diameter, have also been found in fields or woods and reported as mysterious UFOs or UFO evidence. These hollow spheres actually are targets used to calibrate radar sets. One such object, not considered an "UFO" by the finder in this case, but arousing


widespread interest, was found on an Arkansas farm on 3 November 1967. The sphere had been manufactured by the Universal Metal Spinning Company of Albuquerque, N. M. for the Physical Science Laboratory of New Mexico State University at Las Cruces. These spheres, according to the manufacturer, are made of aluminum, vary in diameter from 3-3/16 in. to 28 in., and are deployed from aircraft, balloons, or rockets. In ordinary use, they fall freely, reaching a terminal velocity of about 90 mph. They are normally dropped only in uninhabited regions. Such spheres, found in Australia,were mentioned in an UFO context by Edwards (1967).

A 5-in, metal object found on a lawn in Colorado, near a burned spot its own size where it evidently had struck while still hot, was thought perhaps to have fallen from outer space during the night, since it was not on the lawn when it had been mowed the previous day. This object was easily identified as the power lawn mower's muffler.

Any artifact reportedly found at the site of an alleged UFO landing, collision, or explosion presents the primary problem of establishing a relationship between the artifact and the UFO. During the course of this study reports reaching us of events from which such artifacts might be recovered have invariably been sufficiently vague and uncertain to make doubtful the reality of the event described. Analysis of the artifact is therefore meaningless unless the analysis itself can demonstrate that the artifact is not of earthly origin. Samples of material were submitted to this project from two reported events which occurred during project operation. In one case (42), a tiny irregular piece of thin metal had reportedly been picked up from among the beer-can tabs and other earthly debris in an area beneath the reported location of a hovering UFO. It was said to have been picked up because it was the only object in the area that the local investigator could not identify immediately. Analysis showed the sample to be composed chiefly of iron. No additional effort was made


to prove that it was or was not a piece of corroded metal can, for project investigators saw no reason to assume it was related to the UFO, even if the reported UFO were real. In the other case, two metal samples were submitted, through APRO headquarters, reportedly from the site of an UFO-automobile collision of 16 July 1967. One of these, a tiny piece of thin, rolled metal, was shown by analysis to be an alloy of magnesium, aluminum, and zinc. The other sample, weighing several grams, was an iron--chromium--manganese alloy in unworked, crystalline state. Large crystals extending from one surface suggested this sample had solidified at the edge of a vessel from which the rest of the melt had been poured. Both of these materials could be produced by conventional technology. Proof that they are residue from a strange object would require demonstration that they were actually found at the site; that they were not there prior to the reported UFO event and could not have been brought there by the automobile or by other means subsequent to the event; that there was dependable continuity of custody of samples between discovery and analysis; and that there was, indeed, an UFO involved in the reported event. In other words, the existence of these materials, since they are easily producible by earthly technology, can not serve as evidence that a strange flying object collided with the automobile in question.

One case described at great length in UFO literature (Lorenzen, 1962) emphasizes metal fragments that purportedly fell to earth at Ubatuba, Sao Paulo, Brazil from an exploding extra-terrestrial vehicle. The metal was alleged to be of such extreme purity that it could not have been produced by earthly technology. For that reason, this particular material has been widely acclaimed as a fragment of an exploded flying disc. Descriptions of the material's origin and analyses occupy 46 pages of the Lorenzen book and the material is referred to in a high percentage of UFO writings. These fragments of magnesium metal -- undoubtedly the


most famous bits of physical evidence in UFO lore -- were generously loaned to the Colorado project by Jim and Coral Lorenzen of APRO for analysis.

The story which associated these fragments with an UFO is even more tenuous than most UFO reports, since the observers could never be identified or contacted because of the illegibility of the signature on the letter which described the event. According to the account by Olavo T. Fontes, M.D., a Rio de Janeiro society columnist wrote, under the heading, "A Fragment From a Flying Disc"

We received the letter: "Dear Mr. Ibrahim Sued. As a faithful reader of your column and your admirer, I wish to give you something of the highest interest to a newspaperman, about the flying discs. If you believe that they are real, of course. I didn't believe anything said or published about them. But just a few days ago I was forced to change my mind. I was fishing together with some friends, at a place close to the town of Ubatuba, Sao Paulo, when I sighted a flying disc. It approached the beach at unbelievable speed and an accident, i.e. a crash into the sea seemed imminent. At the last moment, however, when it was almost striking the waters, it made a sharp turn upward and climbed rapidly on a fantastic impulse. We followed the spectacle with our eyes, startled, when we saw the disc explode in flames. It disintegrated into thou sands of fiery fragments, which fell sparkling with magnificent brightness. They looked like fireworks, despite the time of the accident, at noon, i. e. at midday. Most of these fragments, almost all, fell into the sea. But a number of small pieces fell close to the beach and we picked up a large amount of this material - which was as light as paper. I am enclosing a sample of it. I dont know anyone that could be trusted to


whom I might send it for analysis. I never read about a flying disc being found, or about fragments or parts of a saucer that had been picked up. Unless the finding was made by military authorities and the whole thing kept as a top-secret subject. I am certain the matter will be of great interest to the brilliant columnist and I am sending two copies of this letter - to the newspaper and to your home address."

From the admirer (the signature was not legible), together with the above letter, I received fragments of a strange metal.....

Following the appearance of this account, the claim was published that analyses of the fragments, performed by a Brazilian government agency and others, showed the fragments to be magnesium of a purity unattainable by production and purification techniques known to man at that time. If this proved to be true, the origin of the fragments would be puzzling indeed. If it could then be established that the fragments had actually been part of a flying vehicle, that vehicle could then be assumed to have been manufactured by a culture unknown to man.

The first step in checking this claim was independent analysis of the magnesium fragments, and comparison of their purity with commercially produced pure magnesium. A comparison sample of triply sublimed magnesium, similar to samples which the Dow Chemical Company has supplied on request for at least 25 years, was acquired from Dr. R. S. Busk, Research Director of the Dow Metal Products Dept., Midland, Mich. Since it was assumed that extremely small quantities of impurities would need to be measured, neutron-activation analysis was selected as the analytical method. The samples were taken to the National Office Laboratory, Alcohol and Tobacco Tax Division, Bureau of Internal Revenue,


at which the personnel had no special interest in the UFO question. The neutron irradiation and gamma spectrometry were personally observed by this writer. The analysis was performed by Mr. Maynard J. Pro, Assistant Chief, Research and Methods Evaluation, and his associates. Original irradiation data and gamma-spectrometer read-out tapes are preserved in project files.

The material irradiated was a chip broken from the main fragment. It was immersed in HCl to remove surface contamination. After washing, the sample presented a bright, shiny, metallic surface. The absence of chlorine emissions in the gamma-ray spectra after neutron activation showed both that washing had been thorough and that chlorine was not present in the sample itself. The concentrations of eight impurity elements were measured. Results are given in parts per million parts of sample, with limits of error estimated on the basis of greatest conceivable error. The "UFO fragment" compared with the Dow material as follows:

  Parts Per Million
ELEMENT Dow Mg. Brazil UFO

Mn 4.8±0.5 35.0±5.
Al not detected (<5) not detected (<10)
Zn 5.±1. 500.±100.
Hg 2.6±0.5 not detected
Cr 5.9±.12 32.0±10.
Cu 0.4±0.2 3.3±1.0
Ba not detected 160.±20.
Sr not detected 500.±100.


Mn, Al, Zn, Hg, and Cr values were obtained from direct gamma spectrometry and half-life measurement; Cu, Ba, and Sr values were obtained by gamma spectrometry after radiochemical separation of the elements. In the latter cases, known standard samples of these elements were irradiated and analyzed concurrently with the specimen. Results, within the limits of error indicated, should be quite dependable. Since spectrographic analyses routinely performed on purified magnesium show no other elements present at concentrations of more than a few parts per million, the analytical results presented above show that the claimed UFO fragment is not nearly as pure as magnesium produced by known earthly technology prior to 1957, the year of the UFO report.

The neutron activation analysis also was utilized as a means of checking the magnesium isotopic content. The suggestion had been made (Jueneman, 1968) that the fragment might be composed of pure Mg26, and therefore the magnesium isotopic content of this fragment should be determined. The suggestion was based on assumed qualities of such a pure isotope and on a density figure of 1.866 gm/cc, which had been reported for the center of one of the magnesium pieces "as determined in replicate using a Jolly balance" (Lorenzen, 1962). It is interesting that this figure was chosen over the density figure of 1.7513 gm/cc, also reported in the Lorenzen book, which was determined at a US Atomic Energy Commission laboratory by creating a liquid mixture in which the fragment would neither float nor sink, and measuring the density of the liquid. The quantity of Mg27 isotope produced by neutron activation [Mg26 (n, gamma) Mg27, as determined by gamma spectrometry after activation, showed that the Brazil sample did not differ significantly in Mg26 isotope content from other magnesium samples.


Although the Brazil fragment proved not to be pure, as claimed, the possibility remained that the material was unique. The high content of Sr was particularly interesting, since Sr is not an expected impurity in magnesium made by usual production methods, and Dr. Busk knew of no one who intentionally added strontium to commercial magnesium. The sample was, therefore, subjected also to a metallographic and microprobe analysis at the magnesium Metallurgical Laboratory of the Dow Chemical Company, through the cooperation of Dr. Busk and Dr. D. R. Beaman. Again, all work was monitored by this writer. Microprobe analysis confirmed the presence of strontium and showed it to be uniformly distributed in the sample (see Case 4). In all probability, the strontium was added intentionally during manufacture of the material from which the sample came. Metallographic examinations show large, elongated magnesium grains, indicating that the metal had not been worked after solidification from the liquid or vapor state. It therefore seems doubtful that this sample had been a part of a fabricated metal object.

A check of Dow Metallurgical Laboratory records revealed that, over the years, this laboratory made experimental hatches of Mg alloy containing from 0.1% - 40% Sr. As early as 25 March 1940, it produced a 700 gm. batch of Mg containing nominally the same concentration of Sr as was contained in the Ubatuba sample.

Since only a few grams of the Ubatuba magnesium are known to exist, and these could have been produced by common earthly technology known prior to 1957, the existence and composition of these samples themselves reveal no information about the samples' origin. The claim of unusual purity of the magnesium fragments has been disproved. The fragments do not show unique or unearthly composition, and therefore they cannot be used as valid evidence of the extra-terrestrial origin of a vehicle of which they are claimed to have been a part.



4. Conclusion

This project has found no physical evidence which, in itself, clearly indicates the existence in the atmosphere of vehicles of extraordinary nature. Belief in the existence of such vehicles, if such belief is held, must rest on other arguments.




Allen, W. Gordon. Space Craft from Beyond Three Dimensions, Exposition Press: New York, (1959), 51 and 98.

Edwards, Frank. Flying Saucers - Here and Now, Lyle Stuart, Inc.: New York, (1967), 199.

Edwards, Frank. Flying Saucers, Serious Business, Bantam Book 53378, (1966), 41ff.

Flail, Richard H. The UFO Evidence, NICAP publication, (1964), 97.

Jueneman, Frederick B. Private communication to Mrs. Coral Lorenzen, 4 January 1968.

Keel, John A. "Are UFOs Using the Earth For a Garbage Dump?" Flying Saucers, No. 4, Dell Publication, (1967), 32ff.

Lorenzen, Coral E. The Great Flying Saucer Hoax, The William Frederick Press: New York, (1962), 89ff. Also reprinted, paperbound, as Flying Saucers, the Startling Evidence of the Invasion from Outer Space, Signet Book T3058, 104ff.

Lorenzen, Coral and Jim. Flying Saucer Occupants, Signet Book T3205, (1967), 19-32.

Maney, C. A. and R. H. Hall. The Challenge of Unidentified Flying Objects, NICAP publication, (1961), iii.

Michel, Aime. Flying Saucers and the Straight Line Mystery, S. G. Phillips, Inc. : New York, (1958), 170.

Moseley, James W. Saucer News, (Spring 1967).

The Flying Saucer Review, Courier Printing and Publishing Co., Ltd.: Tunbridge Wells, Kent, England, (Sept.-Oct., 1967), 14.