1. Bent, A. C. (1940): Life Histories of North American Cuckoos, Goatsuckers, Hummingbirds and their Allies. Smiths. Inst. 176.
2. Burns, F. L. (1921): Comparative Periods of Nestling Life of some North AmericanNidicolae. Wilson Bull. 33.
3. Goodall, J. D., Johnson, A. W., andPhilippi, B. R. A. (1946): Las Aves de Chile, su conocimiento y sus costumbres. Tomo Primero.
4. Huxley, J. S., Webb, C. S., andBest, A. T. (1939): Temporary poikilothermy in birds. Nature, 14.
5. Lack, D. (1950): The Breeding Biology of the SwiftApus apus. Ibis 92.