(2009) „Bos grunniens and Bos mutus (Artiodactyla: Bovidae)”. Mammalian Species836, 1–17. o. DOI:10.1644/836.1.
(2004) „The naming of wild animal species and their domestic derivatives”. Journal of Archaeological Science31 (5), 645. o. DOI:10.1016/j.jas.2003.10.006.
Wiener, Gerald; Jianlin, Han; Ruijun, Long (2003). "4 The Yak in Relation to Its Environment", The Yak, Second Edition. Bangkok: Regional Office for Asia and the Pacific Food and Agriculture Organization of the United Nations, ISBN 92-5-104965-3. Accessed 8 August 2008.