McLellan, Bruce & Reiner, David C., A review of bear evolution(PDF), Int. Conf. Bear Res. and Manage 9 (1), 1994, 9 (1): 85–96 [2012-05-10], (原始内容存档(PDF)于2017-11-15)
McLellan, Bruce & Reiner, David C., A review of bear evolution(PDF), Int. Conf. Bear Res. and Manage 9 (1), 1994, 9 (1): 85–96 [2012-05-10], (原始内容存档(PDF)于2017-11-15)