1. Notes of an ornithological reconnaissance of portions of Kansas, Colorado, Wyoming, and Utah.;Allen;Bulletin of the Museum of Comparative Zoology,1872
2. Colorado birds: a reference to their distribution and habitat.;Andrews,1992
3. Birds of Colorado.;Bailey,1965
4. Introduction to distance sampling: estimating abundance of biological populations.;Buckland,2001
5. Model selection and multi-model inference: a practical information-theoretic approach.;Burnham,2002