R. P. Feynman

Rev. Mod. Phys. 20, 367 (1948) - Published 1 April, 1948

Armin J. Deutsch

Rev. Mod. Phys. 20, 388 (1948) - Published 1 April, 1948

Carl Eckart

Rev. Mod. Phys. 20, 399 (1948) - Published 1 April, 1948

R. D. Cowan and G. H. Dieke

Rev. Mod. Phys. 20, 418 (1948) - Published 1 April, 1948