Sources

Fishbeck, Dale W., and Aurora M. Sebastiani. Comparative Anatomy: A Vertebrate Dissection Guide. Englewood, CO: Morton Company, 2001.
209-226.
 

Golden, Howard, and J.D. Solf. River Otter. 1194. Alaska Department of Fish and Game. 20 Apr. 2005
http://www.adfg.state.ak.us/pubs/notebook/furbear/rvrotter.php

River Otter. Animal Facts WildWNC.org. 22 Apr. 2005
<http://www.wildwnc.org/af/riverotter.htm>.