1. Einstein, Albert 1924 (archival document ): Letter to Otto Halpern, after 26 August 1924. [In:] Einstein 2015a, Doc. 309, s. 483. Available online: https://einsteinpapers.press.princeton.edu/vol14-doc/585; English translation in:
2. Einstein 2015b, Doc. 309, pp. 312–313. Available online: https://einsteinpapers.press.princeton.edu/vol14-trans/342.
3. Einstein, Albert 1925 (archival document ): Letter to Erwin Schrödinger, 28 February 1925. [In:] Einstein 2015a, Doc. 446, pp. 677–678. Available online: https:// einsteinpapers.press.princeton.edu/vol14-doc/779; English translation in: Einstein 2015b, Doc. 446, pp. 438–439. Available online: https://einsteinpapers.press.princeton.edu/vol14-trans/468.
4. Einstein, Albert 1926 (archival document ): Letter to Paul Ehrenfest, 24 November 1926. [In:] Einstein 2018a, Doc. 420, pp. 641– 643 (do listu na pp. 643–645 dołączony jest manuskrypt nieopublikowanej ostatecznie notki Uchlenbecka i Ehrenfesta 1926a (archival document )). Available online: https://einsteinpapers.press.princeton.edu/vol15-doc/753; English translation in: Einstein 2018b, Doc. 420, pp. 396– 397 (do listu na pp. 397–399 dołączony jest manuskrypt nieopublikowanej ostatecznie notki Uchlenbecka i Ehrenfesta 1926a (archival document )). Available online: https://einsteinpapers.press.princeton.edu/vol15-trans/430.
5. Einstein, Albert 2015a: The Collected Papers of Albert Einstein, Vol. 14. The Berlin Years: Writings & Correspondence, April 1923–May 1925 – Documentary Edition. Edited by Diana Kormos Buchwald, József Illy, Ze’ev Rosenkranz, Tilman Sauer & Osik Moses. Princeton, New Jersey, USA: Princeton University Press. Available online: https://einsteinpapers.press.princeton.edu/vol14-doc/.