Walter G. Dickson (1898). Japan. The Eight Boards of Government (em inglês). Michigan: Peter Fenelon Collier. p. 60
Jien, The Future and the Past: A Translation and Study of the Gukanshō, an Interpretative History of Japan Written in 1219 (em inglês), University of California Press, 1979 p. 268 ISBN 9780520034600.