Maruyama, Toshiaki (1984): Miocene diatom biostratigraphy of onshore sequences on the Pacific side of Northeast Japan, with reference to DSDP Hole 438A; Part 2. Tohoku University, Faculty of Science, Institute of Geology and Paleontology, Sendai, Japan, Science Reports of the Tohoku University. Series 2: Geology = Tohoku Daigaku Rika Hokoku. Dai 2: Shu Chishitsugaku, 55 (1), 77-140, georefid:1986-015482