1. Rings of Differential Operators;Björk,1979
2. Commutative Algebra;Bourbaki,1972
3. High order derivations and primary ideals to regular prime ideals;Brommer;Arch. Math.,1986
4. Groupes Algébrique;Demazure,1970
5. Fourier Analysis in Several Complex Variables;Ehrenpreis,1970