1. 1) Japan Road Association: Specifications for Highway Bridges, Commentary, Part V: Seismic Design, pp. 121-125, 2002. (in Japanese)
2. 2) Committee to Study Countermeasures against Soil Liquefaction, Ministry of Land, Infrastructure, Transport and Tourism: Report of the Verification Result of Evaluation Method for Liquefaction, 2011. http://www.mlit.go.jp/report/press/kanbo08_hh_000154.html. (in Japanese)
3. 3) Study Committee on Engineering Properties and Utilization of Volcanic Ash Soil: Proceedings of the Symposium on Properties of Volcanic Ash Soil and its Design and Execution, The Japanese Geotechnical Society, 1995. (in Japanese)
4. 4) Study Committee on Engineering Issues of Crushable Ground: Study Committee Report and Proceedings of the Symposium on Engineering Issues of Crushable Ground, The Japanese Geotechnical Society, 1999. (in Japanese)
5. 5) Study Committee on Properties and Utilization of volcanic Ash Soil in Hokkaido: Volcanic Ash Soil for Businesses -Properties, Design/Construction, and Disasters-, Hokkaido Branch of the Japanese Geographical Society, 2010. (in Japanese)