Simpson, George Gaylord (1945): "The principles of classification and a classification of mammals". Bulletin of the American Museum of Natural History, 85documento pdfArquivado 29 de xullo de 2016 en Wayback Machine.
Simpson, George Gaylord (1945): "The principles of classification and a classification of mammals". Bulletin of the American Museum of Natural History, 85documento pdfArquivado 29 de xullo de 2016 en Wayback Machine.