1. Ring Theory LNM;J. Alev,1986
2. J.Alev, T.J.Hodges and J.Velez "Fixed rings of Weyl algebras", preprint, University of Cincinnati, 1987.
3. M. Auslander and D.A. Buchsbaum, "On ramification theory in Noetherian rings", Amer. J. Math., 81 (1959), 749–764.
4. A. Beilinson and I.N. Bernstein, "Localization de g-modules" C.R. Acad. Sci. Paris Ser. I 292 (1981), 15–18.
5. A. Beilinson and I.N. Bernstein, "A generalisation of Casselman's submodule theorem", Representation theory of reductive groups, Birkhauser, Boston 1983.