1. The Finite Element Method for Elliptic Problems;Ciarlet,1978
2. Introduction to Approximation Theory;Chenky,1966
3. On the rate of convergence of the Bergman-Vekua method for the numerical solution of elliptic boundary problems;Eisenstat,1972
4. Z. C. Li. On the combination of various finite element methods for solving the boundary value problems of elliptic equations, to appear.
5. On the Ritz-Galerkin-F.E.M. combined method of solving the boundary value problems of elliptic equations;Li;Sci. Sinica,1981