1. Amano, K., Geology of the Ou backbone ranges in Miyagi and Yamagata prefectures, northeast Honshu, Japan, Sci. Rep. Tohoku Univ., Inst. Geol. Pal., Contr., 81, 1–56, 1981.
2. Barron, J. A., Lower Miocene to Quaternary diatom biostratigraphy of Leg 57, off northeast Japan, Deep Sea Drilling Project, Initial Rept. of the DSDP, 56-57, pp. 641–685, 1980.
3. Barron, J. A., H. E. Jr. Harper, G. Keller, R. A. Reynolds, T. Sakai, B. L. Shaffer, and P. R. Thompson, Biostratigraphic summary of the Japan Trench transect, Legs 56 and 57, Deep Sea Drilling Project, Initial Rept. of the DSDP, 56-57, pp. 505–520, 1980.
4. Bowles, F. A., R. N. Jack, and I. S. E. Carmichael, Investigation of deep-sea volcanic ash layers from Equatorial Pacific Cores, Geol. Soc. Am. Bull., 84, 2371–2388, 1973.
5. Cadet, J. P. and K. Fujioka, Neogene volcanic ashes and explosive volcanism: Japan Trench transect, Leg 57, Deep Sea Drilling Project, Initial Rept. of the DSDP, 56-57, pp. 1027–1041, 1980.