McRobie, H.; Thomas, A.; Kelly, J. (2009). «The genetic basis of melanism in the gray squirrel (Sciurus carolinensis)». Journal of Heredity. 100 (6): 709–714. doi:10.1093/jhered/esp059. PMID19643815.
McRobie, H.; Thomas, A.; Kelly, J. (2009). «The genetic basis of melanism in the gray squirrel (Sciurus carolinensis)». Journal of Heredity. 100 (6): 709–714. doi:10.1093/jhered/esp059. PMID19643815.
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Lawniczak, M. (2002). Sciurus carolinensis, Animal Diversity Web. Note especially entries for 'physical description' and 'Other comments'.