Ericson, P.G.P. et al. (2006) Diversification of Neoaves:integration of molecular sequence data and fosils., Biology Letters, nr.2, sid:543-547, doi:10.1098/rsbl.2006.0523.
Dr. Adrian Lombard/International Association for Falconry and Conservation of Birds of Prey (2014-03-08): Facebook-meddelande. Facebook.com. Läst 7 juli 2014. (engelska)