1. Cai L, Wiener G. The yak. Bangkok: RAP Publication; 1995.
2. Zheng PL. Bovine breeds in China. Shanghai: Scientific and Technical Publishers; 1986.
3. Cai L, Sichuan yak. Chengdu: Sichuan Nationalities Publication House; 1989 [in Chinese].
4. Cai L. China yak. Beijing: Agricultural Publication House; 1992 [in Chinese].
5. Joshi DD, Lund PN, Miller DJ, Shestha SK. Yak production in Nepal. In: Proceedings of the First International Congress Yak. Lanzhou, China; 1994, p. 105–12.