Weber, Roy E.; Hiebl, Inge; Braunitzer, Gerhard (1988). "High Altitude and Hemoglobin Function in the Vultures Gyps rueppellii and Aegypius monachus". Biological Chemistry Hoppe-Seyler. 369 (4): 233–240. doi:10.1515/bchm3.1988.369.1.233. PMID3401328.
Tingay, R. E.; Sureda, N. & Gilbert, M. (2008). "Steppe Eagle (Aquila nipalensis) Foraging Behavior in Mongolia: A Combined Use of Diversionary and Covert Ambush Tactics". Journal of Raptor Research. 42 (2): 155–156. doi:10.3356/JRR-07-52.1. S2CID84630689.
Weber, Roy E.; Hiebl, Inge; Braunitzer, Gerhard (1988). "High Altitude and Hemoglobin Function in the Vultures Gyps rueppellii and Aegypius monachus". Biological Chemistry Hoppe-Seyler. 369 (4): 233–240. doi:10.1515/bchm3.1988.369.1.233. PMID3401328.
Tingay, R. E.; Sureda, N. & Gilbert, M. (2008). "Steppe Eagle (Aquila nipalensis) Foraging Behavior in Mongolia: A Combined Use of Diversionary and Covert Ambush Tactics". Journal of Raptor Research. 42 (2): 155–156. doi:10.3356/JRR-07-52.1. S2CID84630689.