1,4-Dihydro-1-ethenyl-6-fluoro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid 1,8-Naphthyridine-3-carboxylic acid, 1,4-dihydro-1-ethenyl-6-fluoro-4-oxo-7-(1-piperazinyl)- 6-Fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1-vinyl-1,8-naphthyridine-3-carboxylic acid 74274-71-8