Robert Krebs (2006), “Francium”, The History and Use of Our Earth's Chemical Elements: A Reference Guide (bằng tiếng Anh), Robert Krebs, tr. 64, ISBN0313334382
doi.org
Maddock, A. G. (1951). “Radioactivity of the heavy elements”. Q. Rev., Chem. Soc. 3: 270–314. doi:10.1039/QR9510500270.