1. N. Anghel, An abstract index theorem on noncompact Riemannian manifolds. Houston J. Math. 19 (1993), 223–237.
2. M.F. Atiyah, Elliptic operators, discrete groups and von Neumann algebras. Soc. Math. France, Astérisque 32–33 (1976), 43–72.
3. M.F. Atiyah, V.K. Patodi, I.M. Singer, Spectral asymmetry and Riemannian geometry I. Math. Proc. Comb. Philos. Soc. 77 (1975), 43–69.
4. D. Barbasch, H. Moscovici, L
2-index and the Selberg trace formula. J. Funct. Analysis 53 (1983), 151–201.
5. G. Carron, Index theorems for noncompact manifolds. J. Reine Angew. Mathematik 541 (2001), 81–115.