Kumagai, Naoichi; Sasajima, Sadao; Ito, Hidebumi (15 Feb 1978). "岩石の長年クリープ実験 : 巨大試片約20年間・小試片約3年間の結果" [Long-term Creep of Rocks: Results with Large Specimens Obtained in about 20 Years and Those with Small Specimens in about 3 Years]. Journal of the Society of Materials Science (Japan) (باليابانية). 27 (293): 157–161. Archived from the original on 2017-07-01. Retrieved 2008-06-16.
Kumagai, Naoichi; Sasajima, Sadao; Ito, Hidebumi (15 Feb 1978). "岩石の長年クリープ実験 : 巨大試片約20年間・小試片約3年間の結果" [Long-term Creep of Rocks: Results with Large Specimens Obtained in about 20 Years and Those with Small Specimens in about 3 Years]. Journal of the Society of Materials Science (Japan) (باليابانية). 27 (293): 157–161. Archived from the original on 2017-07-01. Retrieved 2008-06-16.