1. Categorical Data Analysis
2. Beyer , H. L. 2004 Hawth's analysis tools for ArcGIS, version 3.27 http://www.spatialecology.com/htools
3. Sexual segregation in mountain sheep: resources or predation;Bleich;Wildlife Monographs,1997
4. Evaluating resource selection functions;Boyce;Ecological Modeling,2002
5. The bighorn sheep in the United States, its past, present, and future;Buechner;Wildlife Monographs,1960