2,3,5,8-Tetrahydro-5-ethyl-8-oxofuro(3,2-b)(1,8)naphthyridine-7-carboxylic acid 5-Aethyl-8-oxo-2,3,5,8-tetrahydrofuro(3,2-b)(1,8)naphthyridin-7-carbonsaeure [German] 5-Ethyl-2,3,5,8-tetrahydro-8-oxofuro(3,2-b)(1,8)naphthyridine-7-carboxylic acid 73101-90-3 Furo(3,2-b)(1,8)naphthyridine-7-carboxylic acid, 2,3,5,8-tetrahydro-5-ethyl-8-oxo-