1. Connes, A.,Publ. IHES 62, 257 (1986).
2. Connes, A.,Geometrie Noncommutative, Inter Editions, Paris, 1990.
3. Dubois-Violette, M.,C.R. Acad. Sci. Paris Ser. I 307, 403 (1988).
4. Dubois-Violette, M., Kerner, R., and Madore, J.,J. Math. Phys. 31, 316 (1990).
5. Madore, J., Lectures on Noncommutative Geometry, Orsay preprint, January 1993.