title: Penems and related substances.
mesh_terms: D000900:Anti-Bacterial Agents / Q000266:history* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D002511:Cephalosporins / Q000138:chemical synthesis; D002621:Chemistry; D049673:History, 20th Century; D008968:Molecular Conformation; D010406:Penicillins / Q000266:history; D013237:Stereoisomerism
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D010406:Penicillins