Snyder, N. F. R.; Wiley, J. W. (1976). "Sexual size dimorphism in hawks and owls of North America". Ornithological Monographs. 20 (20): 1-96. doi:10.2307/40166710. JSTOR40166710.
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Snyder, N. F. R.; Wiley, J. W. (1976). "Sexual size dimorphism in hawks and owls of North America". Ornithological Monographs. 20 (20): 1-96. doi:10.2307/40166710. JSTOR40166710.