1. American Ornithologist's Union (AOU). 1992–2000. The Birds of North America: Life Histories for the 21st Century. Academy of Natural Sciences of Philadelphia, Pennsylvania.
2. AOU Checklist of North American birds,1998
3. The Evolution of National Wildlife Law;Bean,1997
4. Putting Biodiversity on the Map: Priority Areas for Global Conservation. International Council for Bird Preservation;Bibby,1992
5. Population Projections for States-by Age, Sex, Race and Hispanic Origin: 1995–2025. US Bureau of the Census;Campbell,1996