Geophagia in Man: Its Nature and Nutritional Effects

JAMES A. HALSTED, M.D.
The American Journal of Clinical Nutrition, Volume 21, Issue 12, December 1968, Pages 1384–1393, https://doi.org/10.1093/ajcn/21.12.1384

https://academic.oup.com/ajcn/article-abstract/21/12/1384/4787956