Koike, H. & Ohe, H. (1997)
Two Sharks (Squalidae) from the Miocene Bessho Formation, Toyoshina, Minamiazumi-gun, Nagano Prefecture Central Japan (abstract). [in Japanese] Abstracts with Programs Regular Meeting, the Palaeontological Society of Japan, 146: 23

Ohe, H. & Koike, H. (1997)
Fishes of the Miocene Bessho Formation, Toyoshina, Minamiazumi-gun, Nagano Pref. (abstract) [in Japanese] Abstracts with Programs Regular Meeting, the Palaeontological Society of Japan, 146: 22

Ohe, F. & Koike, H. (1998)
Fish Assemblage of the Miocene Bessho Formation, Toyoshina-machi, Minamiazumi-gun, Nagano Prefecture. [in Japanese with English abstract] Research Report of the Shinshushinmachi Fossil Museum, 1, 33–42

Koike, H. & Ohe, F. & Narita, K. (2008)
A fossil dermal denticle, Scymnodon ichiharai (Elasmobranchii; Somniosidae) from Miocene Bessho Formation in Azumino City, Nagano Prefecture, Japan. [in Japanese with English abstract] Research Report of the Shinshushinmachi Fossil Museum, 11, 1–13

Takakuwa, Y. & Koike, H. & Narita, K. (2009)
Outline of fossil elasmobranchs from the Middle Miocene Bessho and Aoki Formations, Nagano Prefecture, Japan. [in Japanese with English abstract] Research Report of the Shinshushinmachi Fossil Museum, 13, 7–18