Ecker et al. (2015)

Ecker, M., Botha-Brink, J., Lee-Thorp, J.A., Piuz, A., Horwitz, L.K., Ostrich eggshell as a source of palaeoenvironmental information for the arid interior of South Africa: A case study from Wonderwerk Cave. Palaeoecology of Africa 33, 95-115. PDF