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Bartels, Thomas (2003). "Variations in the morphology, distribution, and arrangement of feathers in domesticated birds". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 298 (1): 91–108. Bibcode:2003JEZB..298...91B. doi:10.1002/jez.b.28. PMID12949771.
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Bartels, Thomas (2003). "Variations in the morphology, distribution, and arrangement of feathers in domesticated birds". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 298 (1): 91–108. Bibcode:2003JEZB..298...91B. doi:10.1002/jez.b.28. PMID12949771.