2,3-Dihydro-5-oxo-1H,5H-pyrido[3,2,1-ij]quinoline-6-carboxylic acid2,3-Dihydro-5-oxo-(1H,5H)-benzo[ij]-quinolizine-6-carboxylic acid6-Carboxy-2,3-dihydro-1H,5H-pyrido[3,2,1-ij]quinolin-5-one3-oxo-3,5,6,7-tetrahydropyrido[3,2,1-ij]quinoline-2-carboxylic acid