References Sibley–Ahlquist taxonomy of birds

clarke, j.a.; tambussi, c.p.; noriega, j.i.; erickson, g.m. & ketcham, r.a. (2005): definitive fossil evidence extant avian radiation in cretaceous. nature 433: 305–308. doi:10.1038/nature03150 pdf fulltext supporting information
sibley, charles gald & ahlquist, jon edward (1990): phylogeny , classification of birds. yale university press, new haven, conn.
on phylogeny , classification of living birds, charles g. sibley
the history of modern birds inferred dna sequences of nuclear , mitochondrial ribosomal genes, marcel van tuinen, charles g. sibley, , s. blair hedges
sibley s classification of birds, eric salzman, birding, december 1993. web version lacks illustrations, show parts of family tree, , includes partial bibliography, adds sequence down tribe level detail on intermediate taxa (especially passerines).