Hackett, SJ, RT Kimball, S Reddy, RCK Bowie, EL Braun, MJ Braun, JL Chojnowski, WA Cox, K-L Han, J Harshman, CJ Huddleston, BD Marks, KJ Miglia, WA Moore, FH Sheldon, DW Steadman, CC Witt, and T Yuri. 2008. A phylogenomic study of birds reveals their evolutionary history. Science 320(5884):1763-1768.