Johnson Kevin P., Sorenson Michael D. (1999): Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence. Auk, 116(3): 792–805. PDF toàn vănLưu trữ 2007-02-05 tại Wayback Machine
Johnson Kevin P., Sorenson Michael D. (1999): Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence. Auk, 116(3): 792–805. PDF toàn vănLưu trữ 2007-02-05 tại Wayback Machine