1. Abrahams, P. W., & Parsons, J. A. (1997). Geophagy in the tropics: An appraisal of three geophagical materials. Environmental Geochemistry and Health, 19(1), 19–22.
2. Agency for Toxic Substances and Disease Registry (ATSDR) (2012). Minimal risk levels.
3. Aufreiter, S., Hancock, R. G. V., Mahaney, W. C., Stambolic, R. A., & Sanmugadas, K. (1997). Geochemistry and mineralogy of soils eaten by humans. International Journal of Food Sciences and Nutrition, 48(5), 293–305.
4. Belitz, H. D., Grosch, W., & Schieberle, P. (2009). Food chemistry. p 425.
5. Bisi-Johnson, M. A., Obi, C. L., & Ekosse, G. E. (2010). Microbiological and health related perspectives of geophagia: An overview. African Journal of Biotechnology, 9(19), 5784–5791.