Robin MD Beck; Olaf RP Bininda-Emonds; Marcel Cardillo; Fu-Guo Robert Liu; Andy Purvis (2006). "A higher level MRP supertree of placental mammals". BMC Evolutionary Biology. 6: 93. PMC 1654192 Freely accessible. PMID 17101039. doi:10.1186/1471-2148-6-93.