Alfred L. Gardner. Curator of North American mammals and Chief of Mammal Section, National Biological Service, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
W. Christopher Wozencraft. Division of Natural Sciences, Bethel College, 1001 W. McKinley Ave., Mishawaka, IN 46545
Banks, R. C., R. W. McDiarmid, and A. L. Gardner 1987-01-01. Resource Publication, no. 166. United States Department of the Interior Fish and Wildlife Service. Washington, D.C., USA. 79. . .
Wilson, Don E., and DeeAnn M. Reeder, eds. 2005-10-01. Mammal Species of the World: A Taxonomic and Geographic Reference, 3rd ed., vols. 1 & 2. Johns Hopkins University Press. Baltimore, Maryland, USA. 2142. 0-8018-8221-4. .
Wilson, Don E., and DeeAnn M. Reeder, eds. 1992-01-01. Mammal Species of the World: A Taxonomic and Geographic Reference, 2nd ed., 3rd printing. Smithsonian Institution Press. Washington, DC, USA. xviii + 1207. 1-56098-217-9. Corrections were made to text at 3rd printing.
Rice, Dale W. 1998-01-01. Special Publications of the Society for Marine Mammals, no. 4. The Society for Marine Mammalogy. Lawrence, Kansas, USA. ix + 231. 1-891276-03-4. .
Wilson & Reeder, eds. (2005): Comments: The close relationship of the four species included herein has been generally recognized by morphological and molecular studies (Goldman et al., 1989; Hendey, 1980a; Kurtén and Anderson, 1980; Shields and Kocher, 1991). Allen (1938) proposed a close relationship between thibetanus and americanus. Thenius (1953), Goldman et al. (1989), and Shields and Kocher (1991) gave support to the monophyly of arctos with maritimus. Synonyms allocated according to McKenna and Bell (1997)