Zeffer, A.; Norberg, U. M. Lindhe (2003-03-15). "Leg morphology and locomotion in birds: requirements for force and speed during ankle flexion". Journal of Experimental Biology. 206 (6): 1085–1097. doi:10.1242/jeb.00208. ISSN0022-0949. PMID12582150.
Zeffer, A.; Norberg, U. M. Lindhe (2003-03-15). "Leg morphology and locomotion in birds: requirements for force and speed during ankle flexion". Journal of Experimental Biology. 206 (6): 1085–1097. doi:10.1242/jeb.00208. ISSN0022-0949. PMID12582150.
Zeffer, A.; Norberg, U. M. Lindhe (2003-03-15). "Leg morphology and locomotion in birds: requirements for force and speed during ankle flexion". Journal of Experimental Biology. 206 (6): 1085–1097. doi:10.1242/jeb.00208. ISSN0022-0949. PMID12582150.