As chemists, we must rename [our] scheme and insert the symbols Ba, La, Ce in place of Ra, Ac, Th. As nuclear chemists closely associated with physics, we cannot yet convince ourselves to make this leap, which contradicts all previous experience in nuclear physics.

'Über den nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle', Die Naturwissenschaften, 1939, 27, 11–15. Trans. J. Heilbron and Robert W. Seidel, Lawrence and his Laboratory: A History of the Lawrence Berkeley Laboratory (1989), Vol. 1, 436–7