1-(1,1-Dioxo-tetrahydro-1lambda*6*-thiophen-3-yl)-6-oxo-1,4,5,6-tetrahydro-pyridazine-3-carboxylic a1-(1,1-Dioxidetetrahydrothien-3-yl)-6-oxo-1,4,5,6-tetrahydropyridazine-3-carboxylic acid1-(1,1-dioxidotetrahydrothiophen-3-yl)-6-oxo-1,4,5,6-tetrahydropyridazine-3-carboxylic acid1-(1,1-dioxidotetrahydro-3-thienyl)-6-oxo-1,4,5,6-tetrahydropyridazine-3-carboxylic acid1-(1,1-dioxidotetrahydrothien-3-yl)-6-oxo-1,4,5,6-tetrahydropyridazine-3-carboxylic acid