Rujukan Neptunium

  1. ↑ Nucleonica (2007–2013). "Universal Nuclide Chart". Nucleonica: Web Driven Nuclear Science. Dicapai 2013-10-15.  (pendaftaran diperlukan).
  2. ↑ Seaborg, G. T. (1994). "Ch. 118. Origin of the actinide concept". dalam K. A. Gschneidner, Jr.; L, Eyring; G. R. Choppin; G. H. Landet. Handbook on the Physics and Chemistry of Rare Earths. 18 – Lanthanides/Actinides: Chemistry. Elsevier. m/s. 4–6, 10–14.