K.-P. Koepfli, M. E. Gompper, E. Eizirik, C.-C. Ho, L. Linden, J. E. Maldonado, R. K. Wayne. Phylogeny of the Procyonidae (Mammalia: Carvnivora): Molecules, morphology and the Great American Interchange. Molecular Phylogenetics and Evolution. 2007, 43 (3): 1076–1095. doi:10.1016/j.ympev.2006.10.003.
A. J. Place, C. I. Abramson. A Quantitative Analysis of the Ancestral Area of Rattlesnakes. Journal of Herpetology. 2004, 38 (1): 152–156. doi:10.1670/103-03N.
Soibelzon, L. H.; Tonni, E. P.; Bond, M. The fossil record of South American short-faced bears (Ursidae, Tremarctinae). Journal of South American Earth Sciences. October 2005, 20 (1–2): 105–113. Bibcode:2005JSAES..20..105S. doi:10.1016/j.jsames.2005.07.005.
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Soibelzon, L. H.; Tonni, E. P.; Bond, M. The fossil record of South American short-faced bears (Ursidae, Tremarctinae). Journal of South American Earth Sciences. October 2005, 20 (1–2): 105–113. Bibcode:2005JSAES..20..105S. doi:10.1016/j.jsames.2005.07.005.