• [Wiki] http://en.wikipedia.org/wiki/Ovis_ammon.
• [AnAge] http://genomics.senescence.info/species/entry.php?species=Ovis_ammon.
• [KeepStaf1966] Keeper, H. and Staff, J. L. (1966). A note on the breeding and hand-rearing of a Marco Polo sheep Ovis ammon poli at London Zoo. International Zoo Yearbook, 6:90--93. doi:10.1111/j.1748-1090.1966.tb01703.x.
• [Kooy2010] Kooijman, S. (2010). Dynamic Energy Budget theory for metabolic organisation. Cambridge Univ. Press, Cambridge.