1. L.I. Mandelstam, N.D. Papalexi, J. Tech. Phys. 7 (1937) 559; (in Russian); Newest Investigations of Propagation of Radio Waves, Collected papers (13 authors), OGIZ, Gostechizdat, Moscow, Leningrad, 1945, 296 p. (there are two papers by Alpert, 1941, 52 p.); L.I. Mandelstam, Izv. Acad. Sci. USSR (Phys. Ser.) (4) (1938) 525.
2. Ya.L. Alpert, B. Gorozhankin, Doklady (Reports of the Academy of Sciences of the USSR, in Russian) b. 49 (4) (1945) 254; R.L. Smith-Rose, Nature (Alpert's letter), 1946, January 12, # 3976.