1. On the L2 n-width of certain classes of functions of several variables;Jerome;J. Math. Anal. Appl.,1967
2. Lectures on Elliptic Boundary Value Problems;Agmon,1965
3. Multiple Integrals in the Calculus of Variations;Morrey,1966
4. Extension of C∞ functions defined in a half space;Seeley,1964