Plumptre, A., Nixon, S., Caillaud, D., Hall, J.S., Hart, J.A., Nishuli, R. & Williamson, E.A.: Gorilla beringei ssp. graueriIUCN Red List of Threatened Species. Version 2016.3. 2016. International Union for Conservation of Nature, IUCN, Iucnredlist.org. Viitattu 3.4.2017. (englanniksi)