1. Problèmes mixtes pour les équations hyperbolique d'ordre supérieur;Agmon,1962
2. A mixed problem with a discontinuous boundary operator for a hyperbolic equation;Cehlov,1975
3. Inequalities in Mechanics and Physics;Duvaut,1976
4. Boundary Value Problems for Elliptic Pseudodifferential Equations;Eskin,1973