[59] Phil. Mag., XXIII (1911), 753.

[60] Le Radium, X (1913), 113, 119.

[61] Sitzungsber. d. k. Bayerischen Akad. d. Wiss. (1913), p. 19.

[62] Ann. d. Phys., XLV, 177; XLVII, 227.

[63] Phys. Rev., X (1918), 283.

[64] Phys. Rev., XVI (1920), 260.

[65] Rays of Positive Electricity (1913), p. 46.

[66] Millikan, Gottschalk, and Kelly, Phys. Rev., XI (1920), 157.

[67] Millikan, Phys. Rev., XVIII (1921), 456. Wilkins, ibid., XXIV (1922), 210.

[68] Phys. Rev., September or October, 1924.