1. Lectures on Elliptic Boundary Value Problems;Agmon,1964
2. Stochastic Differential Equations: Theory and Applications;Arnold,1974
3. Radical differential calculus;Berger,1979
4. A Method of Generalized Characteristics;Berger;Memoirs of the Amer. Math. Soc.,1982
5. Characteristic methods for multidimensional evolution equations;Berger,1983