Griffiths, C. S.; Barrowclough, G. F.; Groth, J. G.; Mertz, L. A. Phylogeny, Diversity, and Classification of the Accipitridae Based on DNA Sequences of the RAG-1 Exon. Journal of Avian Biology. 2007, 38 (5): 587–602. ISSN 0908-8857. doi:10.1111/j.2007.0908-8857.03971.x.
Griffiths, C. S.; Barrowclough, G. F.; Groth, J. G.; Mertz, L. A. Phylogeny, Diversity, and Classification of the Accipitridae Based on DNA Sequences of the RAG-1 Exon. Journal of Avian Biology. 2007, 38 (5): 587–602. ISSN 0908-8857. doi:10.1111/j.2007.0908-8857.03971.x.