Brand, L.; Urbina, M.; Chadwick, A.; DeVries, T. J.; Esperante, R. A high resolution stratigraphic framework for the remarkable fossil cetacean assemblage of the Miocene/Pliocene Pisco Formation, Peru. Journal of South American Earth Sciences. 2011, 31 (4): 414–425. Bibcode:2011JSAES..31..414B. doi:10.1016/j.jsames.2011.02.015.
Brand, L.; Urbina, M.; Chadwick, A.; DeVries, T. J.; Esperante, R. A high resolution stratigraphic framework for the remarkable fossil cetacean assemblage of the Miocene/Pliocene Pisco Formation, Peru. Journal of South American Earth Sciences. 2011, 31 (4): 414–425. Bibcode:2011JSAES..31..414B. doi:10.1016/j.jsames.2011.02.015.