W. Alpízar-Alpízar, R. Sierra, P. Cuenca, C. Une, F. Mena, and G. I. Pérez-Pérez, “Association of the p53 codon 72 polymorphism to gastric cancer risk in a hight risk population of Costa Rica”, Rev. Biol. Trop., vol. 53, no. 3-4, pp. 317–324, Dec. 2005.