The experiment for this letter to the editor was conducted on 13 January 1939; see Richard Rhodes The Making of the Atomic Bomb 263 and 268 (Simon and Schuster, 1986).
A carta ao editor deste experimento foi realizado en 13 de xaneiro de 1939; ver Richard Rodes, The Making of the Atomic Bomb (A fabricación da bomba atòmica), Simon and Schuster, 1986, pp. 263 i 268.