Moody JA, Fasching CE, Sinn LM, Gerding DN, Peterson LR. Comparative efficacy of cefoperazone, cefoperazone plus sulbactam, ciprofloxacin, clindamycin, metronidazole, and penicillin G against anaerobic bacteria in an animal model. J Lab Clin Med. 1990 Feb; 115(2):190-5.