Kaufman DW, Kelly JP, Johannes CB, Sandler A, Harmon D, Stolley PD, Shapiro S. Acute thrombocytopenic purpura in relation to the use of drugs. Blood. 1993 Nov 1;82(9):2714-8.
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.