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Hole, David G.; Willis, Stephen G.; Pain, Deborah J.; Fishpool, Lincoln D.; Butchart, Stuart H. M.; Collingham, Yvonne C.; Rahbek, Carsten; Huntley, Brian (2009). "Projected impacts of climate change on a continent-wide protected area network". Ecology Letters. 12 (5): 420–431. doi:10.1111/j.1461-0248.2009.01297.x. ISSN1461-023X. PMID19379136.
Smith, Thomas Bates (1990). "Comparative Breeding Biology of the Two Bill Morphs of the Black-Bellied Seedcracker". The Auk. 107 (1): 153–160. JSTOR4087813.
Hole, David G.; Willis, Stephen G.; Pain, Deborah J.; Fishpool, Lincoln D.; Butchart, Stuart H. M.; Collingham, Yvonne C.; Rahbek, Carsten; Huntley, Brian (2009). "Projected impacts of climate change on a continent-wide protected area network". Ecology Letters. 12 (5): 420–431. doi:10.1111/j.1461-0248.2009.01297.x. ISSN1461-023X. PMID19379136.
Smith, Thomas Bates (1990). "Patterns of morphological and geographic variation in trophic bill morphs of the African finch Pyrenestes". Biological Journal of the Linnean Society. 41 (4): 381–414. doi:10.1111/j.1095-8312.1990.tb00842.x. ISSN0024-4066.
Hole, David G.; Willis, Stephen G.; Pain, Deborah J.; Fishpool, Lincoln D.; Butchart, Stuart H. M.; Collingham, Yvonne C.; Rahbek, Carsten; Huntley, Brian (2009). "Projected impacts of climate change on a continent-wide protected area network". Ecology Letters. 12 (5): 420–431. doi:10.1111/j.1461-0248.2009.01297.x. ISSN1461-023X. PMID19379136.