Dine JL, Schneider MK, Stewart BR, Armer JM. Learning from traditional healers in South Africa. J Lymphoedema. 2009;4(2):10-6.
Rothman KJ, Velez H, Glass RL, Mejia R, Espinal F. Dental caries and soil contents of trace metals in two Colombian villages. J Dent Res. 1972 Nov 1;51(6):1686.