1. Shale, D.: Trans. Am. Math. Soc.103, 149–167 (1962). In another context see also Weil, A.: Acta Math.111, 143–211 (1963)
2. Leray, J.: Géométrie symplectique et physique mathématique. Aix-en-Provence 1974. Colloq. Intern. Centre Nat. Rech. Sci. Paris237, 253 (1975)
3. Maslov, V. P., Arnold, V., Bouslaiev, V.: Théorie des perturbations et méthodes asymptotiques. Paris: Dunod 1972
4. Souriau, J. M.: Construction explicite de l'indice de Maslov. In: Proceedings of the 4th International Colloquium on Group Theoretical Methods in Physics, Nijmegen 1975. Lecture notes in physics, Vol. 50, p. 117. Berlin-Heidelberg-New York: Springer 1976
5. Feynman, R.P.: Rev. Mod. Phys.20, 367–387 (1948)