1. The taxonomy, distribution and adaptations of recent equids;Equids in the Ancient World,1986
2. Boyd, L., and Houpt, D.A. (1994). Przewalski’s Horse: The History and Biology of an Endangered Species, State University of New York Press.
3. Przewalski’s horse (Equus przewalskii n. sp.);Isvestia Rus. Geogr. Obs. -Va St Petersburg,1881
4. Moehlman, P. (2002). Equids: Zebras, Asses and Horses, IUCN Publications Services Unit. IUCN/SSC Equid Specialist Group.
5. Paige, W. (2016). Smithsonian Magazine, Smithsonian Institution.