The Birds of Newfoundland Labrador
Austin, Oliver L., Jr.
British Birds' Eggs & Nests
Atkinson, Rev. Canon
Catalogue of the Birds of the Americas and Adjacent Islands, Part I, Number 4. Birds of Prey
Hellmayr, Charles E; Conover, Boardman; Cory, Charles B.
Traite de Fauconnerie (French Treatise on Falconry)
SCHLEGEL, Hermann; VERSTER DE WULVERHORST, A.H.