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de Kloet, RS, de Kloet SR (2005). „The evolution of the spindlin gene in birds: Sequence analysis of an intron of the spindlin W and Z gene reveals four major divisions of the Psittaciformes”. Molecular Phylogenetics and Evolution36 (3), 706–721. o. DOI:10.1016/j.ympev.2005.03.013. PMID16099384.