caption: Unknown Illustrator, Turbary or Peat Sheep (ewe). From Ritchie, J. (1920). The influence of man on animal life in Scotland; study in faunal evolution. Cambridge University Press in the public domain.
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.
Ritchie, J. (1920). The influence of man on animal life in Scotland; study in faunal evolution. Cambridge, UK: University Press.
Smithsonian Institution. Board of Regents. (1913). Annual Report of the Board of Regents of the Smithsonian Institution. Washington, DC: Smithsonian Institution.