Guerrero-Preston, Rafael, and Paul Brandt-Rauf. “Pharmaceutical Residues in the Drinking Water Supply: Modeling Residue Concentrations in Surface Waters of Drugs Prescribed in the United States”. Puerto Rico Health Sciences Journal 27, no. 3 (July 22, 2008). Accessed December 18, 2025. https://prhsj.rcm.upr.edu/index.php/prhsj/article/view/75.