5850691 Varley, H. Paul. (1980). A Chronicle of Gods and Sovereigns: Jinnō Shōtōki of Kitabatake Chikafusa. New York: Columbia University Press. ; OCLC 6042764 External links National Diet Library, "The Japanese Calendar" -- historical overview plus illustrative images from library's collection New York Public Library Digital Gallery, early photograph of Shrine steps where Sanetomo was killed Japanese eras 1210s in Japan 1220s in Japan