1. Foundations of Mechanics;Abraham,1994
2. Representations of compact Lie groups and elliptic operators;Brüning;Invent. Math.,1978
3. G-spaces, the asymptotic splitting of L2(M) into irreducibles;Donnelly;Math. Ann,1978
4. Semi-classical weights and equivariant spectral theory;Dryden;Adv. Math.,2014
5. V. Guillemin, Quasi-classical aspects of reductions, in: Proceedings of the Eighth International Congress on Mathematical Physics, World Scientific Publishing, Singapore, pp. 106-119.