1. Cantoni, V.: Commun. math. Phys.44, 125 (1975)
2. Mackey, G. W.: Mathematical foundations of quantum mechanics. New York: Benjamin 1963
3. Lang, S.: Differential manifolds. Reading: Addison Wesley 1972
4. Cantoni, V.: Intrinsic geometry of the quantum-mechanical “phase space”, Hamiltonian systems and correspondence principle. Rend. Accad. Nazl. Lincei, to appear