1. The Finite Element Method for Elliptic Problems;Ciarlet,1978
2. Elliptic Differential Equations (Theory and Numerical Treatment);Hackbusch,1992
3. Iterative Solution Methods;Axelsson,1994
4. Finite Element Solution of Boundary Value Problems;Axelsson,1984
5. Steepest Descent for General Systems of Linear Differential Equations in Hilbert Space;Neuberger,1983