(en) Waltraud Kugler et Elli Broxham, The Ecological Value of Feral Livestock Populations in Europe : Overview, situation and development of a network for management of wild livestock populations, Final Report, SAVE-Project, (lire en ligne), p. 34.
Porter et al. 2016, p. 469. [Porter et al. 2016] (en) Valerie Porter, Lawrence Alderson, Stephen J. G. Hall et Dan Phillip Sponenberg, Mason's World Encyclopedia of Livestock Breeds and Breeding, CAB International, , 6e éd., 1 107 p. (ISBN1-84593-466-0, OCLC948839453).
worldcat.org
Porter et al. 2016, p. 469. [Porter et al. 2016] (en) Valerie Porter, Lawrence Alderson, Stephen J. G. Hall et Dan Phillip Sponenberg, Mason's World Encyclopedia of Livestock Breeds and Breeding, CAB International, , 6e éd., 1 107 p. (ISBN1-84593-466-0, OCLC948839453).