Duval, C., Lecomte, P. and Ovsienko, V.: Conformally equivariant quantization: existence and uniqueness, Ann. Inst. Fourier (Grenoble) 49(6) (1999), 1999-2029.
Duval, C. and Ovsienko, V. Yu.: Space of second-order linear differential operators as a module over the Lie algebra of vector fields, Advances in Math. 132 (1997), 316-333.
Fuks, D. B.: Cohomology of Infinite-Dimensional Lie Algebras, Contemp. Soviet Math., Consultants Bureau, New York, 1986.
Gargoubi, H.and Ovsienko, V. Yu.: Space of linear differential operators on the real line as a module over the Lie algebra of vector fields, Internat. Math. Res. Notices No. 5 (1996), 235-251.
Grozman, P. Ja.: Classification of bilinear invariant operators on tensor fields (in Russian), Funktsional. Anal. i Prilozhen. 14(2) (1980), 58-59.
Lecomte, P. B. A. and Ovsienko, V.: Projectively equivariant symbol calculus, Lett. Math. Phys. 49(3) (1999), 173-196.
Lecomte, P. B. A.: On the cohomology of sl(m + 1) acting on differential operators and sl(m + 1)-equivariant symbol, Indag. Math. NS 11(1) (2000), 95-114.
Lecomte, P. B. A.: Classification projective des espaces d'opérateurs différentiels agissant sur les densités, C.R. Acad. Sci. Paris Série 1 328 (1999), 287-290.
Lecomte, P. B. A., Mathonet, P. and Tousset, E.: Comparison of some modules of the Lie algebra of vector fields, Indag. Math. NS. 7(4) (1996), 461-471.