H. Ogasawara, T. Katsura, G. Hofmann, Y. Yabe, M. Nakatani, M. Naoi, H. Ishii, D. Roberts, S. Nakao, M. Okubo, et al. In situ monitoring of rock mass response to mining in South African gold mines using the Ishii strainmeters. Proceedings of 6th South African Rock Engineering Symposium SARES 2014. 2014. 21-34
S.Nakao, Y.Morita and Y.Hirata, Crustal deformation in dense network by using newly developed GPS system,. Monthly Earth, Gogai No.25, 187-191, 1999
A.Mukai, K.Fujimori, H.Ishii, S.Nakao, S.Matsumoto and Y.Hirata, Variations of Strain and tilt observed at on 800m Borthole on Awaji Island,. Jor.Geod.Soc, Japan 44, 237-248, 1998