1. a J. S. Kiely, E. Laborde, L. Lesheski, T. Culbertson and J. Sesnie, 3rd International Symposium on New Quinolones, Vancouver, Canada, July 1990, Abstract 25.
2. b G. Y. Lecher, European Patent 306,860 (1989).
3. Chem. Abstr., 111, 78016 (1989).
4. c T. Himmler, M. Schriewer, U. Petersen, K. Grohe, I. Haller, K. G. Metzger, R. Endermann and H. J. Zeiler, German Patent 3,816,119 (1989).
5. Chem. Abstr., 112, 216720 (1990).