Baldwin, S. P., Oberholser, H. C. & Worley, L. G. 1931. Measurements of Birds. Scientific Publications of the Cleveland Museum of Natural History Vol. 2. Contribution No.17 from the Baldwin Bird Research Laboratory. Cleveland, Ohio.
Dunstan, T. C. 1972. A Harness for Radio-tagging Raptorial Birds. Inland Bird Banding News 44: 4-8.
Jameson, E. W., Jr. & Peeters, H. J. 1977. An Introduction to Hawking. Davis, California.