Boveng, P.: Phoca larghaIUCN Red List of Threatened Species. Version 2016.2. 2016. International Union for Conservation of Nature, IUCN, Iucnredlist.org. Viitattu 6.9.2016. (englanniksi)
umich.edu
animaldiversity.ummz.umich.edu
Robert Abar: Phoca larghaAnimal Diversity Web. University of Michigan Museum of Zoology. Viitattu 19.7.2011. (englanniksi)