1. Niels Bohr, letter to Pauli, 1 July 1929, with draft about α-decay, Niels Bohr Archive, Copenhagen.
2. Niels Bohr, note Beta Ray Spectra and Energy Conservation, Niels Bohr Archive.
3. W. Pauli, letter to Niels Bohr, 17 July 1929, Niels Bohr Archive.
4. Niels Bohr, Faraday Lecture, J. Chem. Soc. (1932): 349.
5. Laurie Brown, Physics Today, Sept. 1978: p. 23.