"Echoes from the Atmosphere," Bell Laboratories Record, Vol. 25, No. 2, Feb. 1947, p. 5.
Friend, A.W. "Theory and Practice of Tropospheric Sounding by Radar," Proceedings of the Institute of Radio
Engineers, Vol. 37, No. 2, Feb. 1949. p. 116.
Friis, H. T,. "Radar Reflections from the Lower Atmosphere," Proceedings of the Institute of Radio Engineers, Vol.
35, No. 5, May 1947, p. 494.
Goldstein, Herbert, "Origin of the Echo," in "Propagation of Short Radio Waves," Massachusetts Institute of
Technology Radiation Laboratory Series, McGraw-Hill Publishing Company, New York, 1951, Vol. 13 edited by Donald E.
Kerr, Chapter 7, pp. 593-595.
Gordon, W. E., "A Theory of Radar Reflections from the Lower Atmosphere," Proceedings of the Institute of Radio
Engineers, Vol. 37, No. 1, Jan. 1949, p. 41.
Gould, William B., "Radar Reflections from the Lower Atmosphere," Proceedings of the Institute of Radio
Engineers, Vol. 35, No. 10, Oct. 1947, p. 1105.
Humphreys, W. J., "Physics of the Air," McGraw-Hill Publishing Cornpany, New York, 1940.
"Many Potential 'Saucers,' " Science News Letter, Vol. 62, No. 7, Aug. 16, 1952, p. 106.
"Radar Returns from the Lower Atmosphere Viewed on an AN/GNP-2 Screen," Landing Aids Experiment Station Progress
Report, 1948 Test Section, Electronics, pp. 22-24.