Loewe, Michael and Edward L. Shaughnessy (1999). The Cambridge History of Ancient China Cambridge University Press. ISBN0-521-47030-7. Page 72, see: [2]
De Bary, William Theodore (2001). Sources of Chinese Tradition: From 1600 Through the Twentieth Century. Published by Columbia University Press. ISBN0-231-11271-8. p. 364.[3]
Needham, Joseph. (1972). Science and Civilization in China: Volume 1, Introductory Orientations. Richmond: Kingprint Ltd., reprinted by permission of the Cambridge University Press with first publication in 1954. ISBN0-521-05799-X. Page 88, see: here.