Michelle Spaulding, Maureen A. O’Leary, John Gatesy: Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution. PLoS ONE 4 (9), 2009, S. e7062, doi:10.1371/journal.pone.00070622009.
