A. J. Dempster
Phys. Rev. 18, 415 (1921) - Published 1 December, 1921
R. V. L. Hartley and Thornton C. Fry
Phys. Rev. 18, 431 (1921) - Published 1 December, 1921
Otto Koppius
Phys. Rev. 18, 443 (1921) - Published 1 December, 1921
R. A. Millikan
Phys. Rev. 18, 456 (1921) - Published 1 December, 1921
E. H. Kurth
Phys. Rev. 18, 461 (1921) - Published 1 December, 1921