(en) Alexander von Humboldt, Aspects of Nature in Different Lands and Different Climates, Psychology Press, (ISBN978-0-415-28933-7, lire en ligne)
(en) Mackenzie Cooley, The Perfection of Nature: Animals, Breeding, and Race in the Renaissance, University of Chicago Press, (ISBN978-0-226-82228-0, lire en ligne)
(en) Charles Hamilton Smith, The Natural History of Dogs: Canidæ Or Genus Canis of Authors. Including Also the Genera Hyæna and Proteles, W.H. Lizars, ... S. Highley, ... London; and W. Curry, jun. and Company Dublin., (lire en ligne)
Desmond Morris, Dogs: the ultimate dictionary of over 1,000 dog breeds, North Pomfret, Vt., Trafalgar Square Pub, , 591–592p. (ISBN1-57076-219-8, OCLC49515650)