V. Barbu, Optimal control of variational inequalities, Research Notes in Mathematics, vol.100, 1984.

V. Barbu, Precupanu T. Convexity and optimization in Banach spaces, 1978.

P. G. Ciarlet, Numerical analysis of the finite element method, Les Presses de l, 1976.

L. A. Caffarelli and A. Friedman, The two-obstacle problem for the biharmonic operator, Annali della Scuola Normale Superiore di Pisa-Classe di Scienze, pp.151-184, 1979.
DOI : 10.2140/pjm.1982.103.325

G. Duvaut and J. Lions, Les inéquations en mécanique et en physique, Travaux et Recherches Mathematiques, N. 21. Dunod, 1972.

R. Glowinski, Numerical Methods for Nonlinear Variational Problems, 1984.

F. Hatch, Freefem documetation, Laboratoire Jacques-Louis Lions, 2013.

D. R. Merlu¸sc?merlu¸sc?-a, A duality algorithm for the obstacle problem, Annals of the Academy of Romanian Scientists, vol.5, issue.12, pp.209-215, 2013.

D. R. Merlu¸sc?merlu¸sc?-a, A duality-type method for the obstacle problem, pp.181-195, 2013.

D. R. Merlu¸sc?merlu¸sc?-a, A Duality-Type Method For The Fourth Order Obstacle Problem, submitted to U, P.B. Sci. Bull

C. M. Murea and D. Tiba, Abstract, Journal of Numerical Mathematics, vol.24, issue.4, 2012.
DOI : 10.1515/jnma-2015-0048

P. Neittaanmaki, J. Sprekels, and D. Tiba, Optimization of elliptic systems, Theory and applications, 2006.

M. C. Ockendon and J. R. Elliot, Weak and variational methods for moving boundary problems, 1982.

J. F. Rodrigues, Obstacle problems in mathematical physics, 1987.

A. Wächter and L. T. Biegler, On the implementation of an interior-point filter line-search algorithm for large-scale nonlinear programming, Mathematical Programming, vol.10, issue.1, pp.25-57, 2006.
DOI : 10.1007/s10107-004-0559-y