found: Kadokawa Nihon chimei d.j. (Ishikawa-ken), 1981:p. 666, etc. (under Niikawa-ken: Toyama-ken, est. July 1871; name changed to Niikawa-ken, Nov. 1871; absorbed by Ishikawa-ken in 1876; became Toyama-ken again in 1887)
notfound: Kyū Niikawa kenshikō Umiuchi Hatasu kankei monjo, 1999: p. 2 (est. 1871; absorbed by Ishikawa-ken in 1876)
found: GeoNames, algorithmically matched, 2009(adm1; 36°30ʹ00ʺN 137°30ʹ00ʺE)
found: ClassWeb, July 10, 2020(Toyama; covers the former Etchū province; DS894.59.T69-.T6995)