Kirwan, G. M.; Schweizer, M.; Copete, J. L.

Multiple Lines of Evidence Confirm That Hume’s Owl Strix butleri (A. O. Hume, 1878) Is Two Species, With Description of an Unnamed Species (Aves: Non-Passeriformes: Strigidae)

. Zootaxa 2015, 3904, 28–50.