(EN) MICHAEL F. L'annunziata, 1 - NUCLEAR RADIATION, ITS INTERACTION WITH MATTER AND RADIOISOTOPE DECAY, Academic Press, 1º gennaio 2003, pp. 68-69, DOI:10.1016/b978-012436603-9/50006-5, ISBN 978-0-12-436603-9. URL consultato il 6 aprile 2024.
«I call (them) “isotopes” or “isotopic elements”, because they occupy the same place (from the Greek) in the periodic table. They are chemically identical, and save only as regards the relatively few physical properties which depend on atomic mass directly, physically identical also.»
