University of Arizona
University of Arizona Press: Adobe and Rammed Earth Buildings
Complete description of the book, "Adobe and Rammed Earth Buildings." A great resource to assist in the study of shelter. Read an excerpt of the book, and a summary as well.
Other
Aircav: Shelters
Informative site explaining what a shelter is and how to best construct a shelter. It also explores the types of shelters possible for construction in a survival setting.