[IX-1] Michel, A. Flying Saucers and the Straight Line Mystery. New York: Criterion Books, 1958.

[IX-2] Air Force Files.

[IX-3] El Paso (Texas) Times, Nov. 4, 1957.

[IX-4] Barker, G. “Chasing the Flying Saucers,” Flying Saucers (May 1958), p. 20 ff.

[IX-5] Denver Post, Nov. 6, 1957.

[IX-6] Viemeister, P. E. The Lightning Book. Garden City, N.Y.: Doubleday & Co., 1961.

[IX-7] Matthias, B. T., and Buchsbaum, S. J. “Pinched Lightning,” Nature, Vol. 194 (1962), p. 327.

[IX-8] Ritchie, D. J. Ball Lightning. A Collection of Soviet Research in English Translation (1961). New York: Consultants Bureau.

[IX-8a] Cade, C. M. “Thunderbolts as the X-weapon,” Discovery, Vol. XXIII (1962), pp. 23–28.

[IX-9] Kapitsa, P. L. “The Nature of Ball Lightning,” Dokl. Akad. Nauk SSSR, Vol. CI, No. 2 (1955), pp. 245–48. (Translated in [IX-8].)

[IX-10] Hill, E. L. “Ball Lightning as a Physical Phenomenon,” Bulletin American Meteorology Society, Vol. XXXXI (1960), p. 199.

[IX-11] Pierce, E. T.; Nadile, R. M.; and McKinnon, P. J. “An Experimental Investigation of Negative Point-plane Corona and Its Relation to Ball Lightning,” AFCRL-TR-60-354. Bedford, Mass.: Oct. 24, 1960.

[IX-12] Gold, E. “Thunderbolts: The Electric Phenomena of Thunderstorms,” Nature, Vol. CLXIX (1952), pp. 561–63.

[IX-13] Kogan-Beletskii, G. I. “The Nature of Ball Lightning,” Priroda, No. 4 (1957), pp. 71–73. (Translated in [IX-8].)

[IX-14] Schmidt, R. O. “The Kearney Incident,” Flying Saucers (October 1959), p. 31 ff.

[IX-15] UFO Critical Bulletin, Vol. II, No. 2 (March-April 1958).

[IX-16] “The Case of the Radioactive UFO,” Flying Saucers (February 1958), p. 30.

[IX-17] “Electro-magnetic Effects Associated With Unidentified Flying Objects (UFO’s),” Subcommittee of the National Investigations Committee on Aerial Phenomena (NICAP), Washington, D.C. (June 1960).

[IX-17a] Sky and Telescope, Vol. XXIII (1962), p. 323.

[IX-18] Michel, A. The Truth about Flying Saucers. New York: Criterion Books, 1956.

[IX-19] Keyhoe, D. E. The Flying Saucer Conspiracy. New York: Henry Holt & Co., 1955.

[IX-20] Scully, F. Behind the Flying Saucers. New York: Popular Library, 1951.

[IX-21] Cramp, L. G. Space, Gravity and the Flying Saucer. New York: British Book Centre, 1955.