1. The mechanical properties of feather keratin;Bonser;J Zool,1996
2. Additional observations on the structure of unusual feather tips;Brush;Wilson Bull,1967
3. Modifications and adaptations to function in feathers of Circus hudsonius;Chandler;Univ Calif Publ Zool,1914
4. Rictal bristle function in willow flycatcher;Conover;Condor,1980
5. On the function of rictal bristles, with reference to Nigerian birds;Dyer;Bull Nigerian Orn Soc,1976