S. W. Simpson, N. E. Levin, J. Quade, M. J. Rogers, and S. Semaw. Ardipithecus ramidus postcrania from the Gona Project area, Afar Regional State, Ethiopia. J. Hum. Evol., volume 129, pages 1-45, April 2019.

S. W. Simpson, L. Kleinsasser, J. Quade, N. E. Levin, W. C. McIntosh, N. Dunbar, S. Semaw, and M. J. Rogers. Late Miocene hominin teeth from the Gona Paleoanthropological Research Project area, Afar, Ethiopia. J. Hum. Evol., volume 81, pages 68-82, April 2015.

T. E. Cerling, N. E. Levin, J. Quade, J. G. Wynn, D. L. Fox, J. D. Kingston, R. G. Klein, and F. H. Brown. Comment on the paleoenvironment of Ardipithecus ramidus. Science, volume 328, issue 5982, pages 1105;authorreply1105, May 2010.

N. E. Levin, S. W. Simpson, J. Quade, T. E. Cerling, and S. R. Frost. Herbivore enamel carbon isotopic composition and the environmental context of Ardipithecus at Gona, Ethiopia. The geology of early humans in the Horn of Africa, Geological Society of America Special Paper, volume 446, pages 215-234, 2008.