(6R,7R)-7-AMINO-3-[[(1,3,4-THIADIAZOL-5-YL)THIO]METHYL]-3-CEPHEM-4-CARBOXYLIC ACID, (6R-trans)-7-amino-8-oxo-3-[(1,3,4-thiadiazol-2-ylthio)methyl]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, Ceftezole Impurity 3, (6R)-7t-amino-8-oxo-3-[1,3,4]thiadiazol-2-ylsulfanylmethyl-(6rH)-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 7-amino-8-oxo-3-(1,3,4-thiadiazol-2-ylsulfanylmethyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, (6R,7R)-7-Amino-8-oxo-3-([1,3,4]thiadiazol-2-ylsulfanylmethyl)-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid