1. Notes on Crystalline Cohomology;Berthelot,1978
2. On the embedding of derivations of finite rank into derivations of infinite rank;Brown;Osaka J. Math.,1978
3. The integrability of the characteristic variety;Gabber;Am. J. Math.,1981
4. Lie Algebras;Jacobson,1979
5. Integrable derivations;Matsumura;Nagoya Math. J.,1982