Jonge; Pauwels, E. K. (1996). "Technetium, the missing element". European Journal of Nuclear Medicine23 (3): 336–44. doi:10.1007/BF00837634. பப்மெட்:8599967.
Yoshihara, H. K. (2004). "Discovery of a new element 'nipponium': re-evaluation of pioneering works of Masataka Ogawa and his son Eijiro Ogawa". Spectrochimica Acta Part B59 (8): 1305–1310. doi:10.1016/j.sab.2003.12.027. Bibcode: 2004AcSpe..59.1305Y.
Yoshihara, H. K. (2004). "Discovery of a new element 'nipponium': re-evaluation of pioneering works of Masataka Ogawa and his son Eijiro Ogawa". Spectrochimica Acta Part B59 (8): 1305–1310. doi:10.1016/j.sab.2003.12.027. Bibcode: 2004AcSpe..59.1305Y.
Jonge; Pauwels, E. K. (1996). "Technetium, the missing element". European Journal of Nuclear Medicine23 (3): 336–44. doi:10.1007/BF00837634. பப்மெட்:8599967.