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, vol. 27, no. 3, July 2008, https://prhsj.rcm.upr.edu/index.php/prhsj/article/view/75.