1. 6-APA, 7-ADCA and other Penicillin Transformation Products;Barber,1986
2. Chemical Stability of Pharmaceuticals. A Handbook for Pharmacists;Connors,1979
3. β-lactamase inhibitors from laboratory to clinical;Bush;Microb. Rev.,1988
4. Doyle, F. P. British Pat. 902,703; Aug. 1962.