Hawk Migration - websites
Thermals - explanation of thermals and birds
Southernskies.net - Gary Taylor discusses thermal structure and aerodynamics
Through the lens Radio Controlled Soaring at DroneyBee.com
Careau, V., J.F. Therrien, P. Porras, D. Thomas, K. Bildstein. 2006. Soaring and gliding flight of migrating Broad-winged Hawks: behavior in the Arctic and Neotropics compared. Wilson Journal of Ornithology 118(4): 471-477.
Hawk Identification Books
A Field Guide to Hawks of North America by William S. Clark and Brian K. Wheeler, Houghton Mifflin, Second Edition (2001).
Hawks from Every Angle: How to Identify Raptors in Flight by Jerry Liguori, Princeton University Press (2005).
Hawks in Flight by Pete Dunne, David Sibley, and Clay Sutton, Houghton Mifflin (1988).
Hawk Watch: A Guide for Beginners by Pete Dunne, Debbie Keller, and Rene Kochenberger, Cape May Bird Observatory (2002).
A Photographic Guide to North American Raptors by Brian K. Wheeler and William S. Clark, Academic Press (1995).
Hawks at a Distance: Identification of Migrant Raptors by Jerry Liguori with a foreword by Pete Dunne