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von Campenhausen, Mark; Wagner, Hermann (1 October 2006). "Influence of the facial ruff on the sound-receiving characteristics of the barn owl's ears". Journal of Comparative Physiology A. 192 (10): 1073–1082. doi:10.1007/s00359-006-0139-0. PMID16721575.
Prum, Richard O.; Brush, Alan H. (September 2002). "The Evolutionary Origin and Diversification of Feathers". The Quarterly Review of Biology. 77 (3): 261–295. doi:10.1086/341993. PMID12365352.
Koch, U. R.; Wagner, H. (2002). "Morphometry of auricular feathers of barn owls (Tyto alba)". European Journal of Morphology. 40 (1): 15–21. doi:10.1076/ejom.40.1.15.13957. PMID12959344.