	Authors	Year	Title
	Ehiro	2002	A time gap at the Permian-Triassic boundary in the South Kitakami Belt, Northeast Japan: An examination based on ammonoid fossils. Saito-Ho-on Kai Museum Research Bulletin, 68: 1-12, 3 fig.
	Murata & Bando	1975	Discovery of Late Permian Araxoceras from the Toyoma Formation in the Kitakami Massif, Northeast Japan. Transactions and Proceedings of the Palaeontological Society of Japan, N.S., 97: 22-31, fig.1-6; Tokyo.