Porter, V. & Mason, I. L. (2002). Mason’s World Dictionary of livestock breeds, types and varieties (5th ed.). Wallingford, Oxfordshire, UK: CABI.
Porter, V., Alderson, L., Hall, S. J. G., & Sponenberg, D. P. (2016). Mason’s World Encyclopedia of Livestock Breeds and Breeding: 2 volume pack (1st ed.). Wallingford, Oxfordshire, UK: CABI.