1. ARNOLD D. N., DOUGLAS J. and GUPTA C. P., A Family of Higher Order Mixed Finite Element Methods for Plane Elasticity, Numer. Math., 45, 1-22 (1984).1329507618790558.73066
2. BABUSKA I., Error-bounds for Finite Element Method, Numer. Math., 16, 322-333 (1971).1320372889710214.42001
3. BREZZI F., On the existence, uniqueness and approximation of saddle-point problems arising from Lagrangian multipliers, RAIRO Model. Math. Anal. Numér., 8, 129-151 (1974).1932553652870338.90047
4. CIARLET P. G., The Finite Element Method for Elliptic Problems, North-Holland (1978).5201740383.65058
5. CLEMENT P., Approximation by finite elements using local regularization, RAIRO Modél. Math. Anal. Numér., 8, 77-84 (1975).1932714007390368.65008