Sergio L. Pereira; Kevin P. Johnson; Dale H. Clayton; Allan J. Baker (2007). “Mitochondrial and nuclear DNA sequences support a Cretaceous origin of Columbiformes and a dispersal-driven radiation in the Paleogene”. Systematic Biology56 (4): 656–672. doi:10.1080/10635150701549672. PMID17661233.
Sergio L. Pereira; Kevin P. Johnson; Dale H. Clayton; Allan J. Baker (2007). “Mitochondrial and nuclear DNA sequences support a Cretaceous origin of Columbiformes and a dispersal-driven radiation in the Paleogene”. Systematic Biology56 (4): 656–672. doi:10.1080/10635150701549672. PMID17661233.