^“Semisynthetic cephalosporins. Synthesis and structure-activity relationships of analogues with 7-acyl groups derived from 2-(cyanomethylthio)acetic acid or 2-[(2,2,2-trifluoroethyl)thio]acetic acid and their sulfoxides and sulfones”. Journal of Medicinal Chemistry20 (1): 30–5. (January 1977). doi:10.1021/jm00211a006. PMID319233.