Melo, Martim; O'ryan, Colleen (). „Genetic differentiation between Príncipe Island and mainland populations of the grey parrot (Psittacus erithacus), and implications for conservation”. Molecular Ecology. 16 (8): 1673–1685. Bibcode:2007MolEc..16.1673M. doi:10.1111/j.1365-294X.2006.03128.x. PMID17402982.
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Melo, Martim; O'ryan, Colleen (). „Genetic differentiation between Príncipe Island and mainland populations of the grey parrot (Psittacus erithacus), and implications for conservation”. Molecular Ecology. 16 (8): 1673–1685. Bibcode:2007MolEc..16.1673M. doi:10.1111/j.1365-294X.2006.03128.x. PMID17402982.
Melo, Martim; O'ryan, Colleen (). „Genetic differentiation between Príncipe Island and mainland populations of the grey parrot (Psittacus erithacus), and implications for conservation”. Molecular Ecology. 16 (8): 1673–1685. Bibcode:2007MolEc..16.1673M. doi:10.1111/j.1365-294X.2006.03128.x. PMID17402982.
Gill, Frank; Donsker, David; Rasmussen, Pamela, ed. (ianuarie 2022). „Parrots, cockatoos”. IOC World Bird List Version 12.1. International Ornithologists' Union. Accesat în .