Rifkin, R. F., Dayet, L., Queffelec, A., Summers, B., Lategan, M., & d’Errico, F. (2015). Evaluating the Photoprotective Effects of Ochre on Human Skin by In Vivo SPF Assessment: Implications for Human Evolution, Adaptation and Dispersal. PLoS One.

Rifkin, Riaan F., Laure Dayet, Alain Queffelec, Beverley Summers, Marlize Lategan, ja Francesco d’Errico. "Evaluating the Photoprotective Effects of Ochre On Human Skin By In Vivo SPF Assessment: Implications for Human Evolution, Adaptation and Dispersal." PLoS One 2015.

Rifkin, Riaan F., et al. "Evaluating the Photoprotective Effects of Ochre On Human Skin By In Vivo SPF Assessment: Implications for Human Evolution, Adaptation and Dispersal." PLoS One 2015.