Mangel AW, Wang J, Sherrill B, Gnanasakthy A, Ervin C, Fehnel SE. Urgency as an endpoint in irritable bowel syndrome. Gastroenterology Research. 2011 Feb 1;4(1):9-12.
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.