1. Numerical solution of boundary value problems by the perturbed variational principle;Babuška;University of Maryland Tech. Note BN-624,1969
2. A linear control problem for a system governed by a partial differential equation;Bossavit,1969
3. Rayleigh-Ritz-Galerkin methods for Dirichlet's Problem using subspaces without boundary conditions;Bramble;Comm. Pure Appl. Math.,1970
4. Approximate Solutions of some Variational Inequalities with Order of Convergence Estimates;Falk,1971
5. Contrôle Optimal de Systèmes Gouvernés par des$́Equations aux Dérivées Partielles;Lions,1968