Synonyms: 4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid, 6-(2-carboxy-2-phenylacetamido)-3,3-dimethyl-7-oxo-, 6-benzyl ester,sodium salt (8CI); Malonamic acid,N-(2-carboxy-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-6-yl)-2-phenyl-,1-benzyl ester, sodium salt (7CI)