1. Sobolev Spaces;Adams,1975
2. Lectures on Elliptic Boundary Value Problems;Agmon,1965
3. Function analysis and periodic solutions of nonlinear differential equations;Cesari;Contrib. diff. Eqns,1963
4. Functional Analysis, Nonlinear Differential Equations and the Alternative Method. Nonlinear Functional Analysis and Differential Equations;Cesari,1976
5. Periodic solutions of nonlinear wave equations;Cesari;Archs ration. Mech. Analysis,1983