↑Sheft, Irving; Fried, Sherman (1950). New Neptunium Compounds (dalam bahasa Inggris). U.S. Atomic Energy Commission, Technical Information Division. hlm.4. Diakses tanggal 5 February 2024.
↑Standard X-ray Diffraction Powder Patterns (dalam bahasa Inggris). U.S. Department of Commerce, National Bureau of Standards. 1953. hlm.64. Diakses tanggal 5 February 2024.
↑Sheft, Irving; Fried, Sherman (1950). New Neptunium Compounds (dalam bahasa Inggris). U.S. Atomic Energy Commission, Technical Information Division. hlm.740. Diakses tanggal 5 February 2024.