Ambartsumian and Ivanenko (1930) "Об одном следствии теории дирака протонов и электронов" (On a Consequence of the Dirac Theory of Protons and Electrons), Доклады Академии Наук СССР (Doklady Akademii Nauk SSSR / Proceedings of the USSR Academy of Sciences) Ser. A, no. 6, pages 153-155. Available in Russian on-line. (页面存档备份,存于互联网档案馆)
Bothe, W.; Becker, H. Künstliche Erregung von Kern-γ-Strahlen [Artificial excitation of nuclear γ-radiation]. Zeitschrift für Physik. 1930, 66 (5–6): 289. Bibcode:1930ZPhy...66..289B. doi:10.1007/BF01390908.
Becker, H.; Bothe, W. Die in Bor und Beryllium erregten γ-Strahlen [Γ-rays excited in boron and beryllium]. Zeitschrift für Physik. 1932, 76 (7–8): 421. Bibcode:1932ZPhy...76..421B. doi:10.1007/BF01336726.
Bothe, W.; Becker, H. Künstliche Erregung von Kern-γ-Strahlen [Artificial excitation of nuclear γ-radiation]. Zeitschrift für Physik. 1930, 66 (5–6): 289. Bibcode:1930ZPhy...66..289B. doi:10.1007/BF01390908.
Becker, H.; Bothe, W. Die in Bor und Beryllium erregten γ-Strahlen [Γ-rays excited in boron and beryllium]. Zeitschrift für Physik. 1932, 76 (7–8): 421. Bibcode:1932ZPhy...76..421B. doi:10.1007/BF01336726.
Ambartsumian and Ivanenko (1930) "Об одном следствии теории дирака протонов и электронов" (On a Consequence of the Dirac Theory of Protons and Electrons), Доклады Академии Наук СССР (Doklady Akademii Nauk SSSR / Proceedings of the USSR Academy of Sciences) Ser. A, no. 6, pages 153-155. Available in Russian on-line. (页面存档备份,存于互联网档案馆)