Journal of Mathematical Sciences: Advances and Applications[1] A. Friedman, Variational Principles and Free Boundary Value
Problems, Wiley-Interscience, New York, 1983.
[2] J. Heinonen, T. Kilpelainen and O. Martio, Nonlinear Potential
Theory of Degenerate Elliptic Equations, Oxford Univ. Press, Oxford,
1993.
[3] S. Karamardian, Generalized complementarity problem, J. Opim.
Theory Appl. 8(3) (1971), 161-168.
DOI: https://doi.org/10.1007/BF00932464
[4] D. Kinderlehrer and G. Stampacchia, Convex Programming and
Variational Inequalities and their Applications, Academic Press, New
York, 1980.
[5] O. Mancino and G. Stampacchia, Convex programming and variational
inequalities, J. Optim. Theory Appl. 9(1) (1972), 3-23.
DOI: https://doi.org/10.1007/BF00932801
[6] J. F. Rodrigues, Obstacle problems in mathematical physics, In:
Mathematics Studies, 134, Elsevier (1987).
[7] A. Szulkin, Minimax principles for lower semicountinuous functions
and application to nonlinear boundary value problems, Ann. Inst. H.
Poincaré Anal. Nonlinéaire 3(2) (1986), 77-109.
[8] G. M. Troianiello, Elliptic Differential Equations and Obstacle
Problems, The University Series in Mathematics, 1987.
[9] M. Willem, Minimax Theorems, Birkhäuser, Berlin, 1996.
[10] A. Ambrosetti and P. H. Rabinowitz, Dual variational methods in
critical point theory and applications, J. Funct. Anal. 14(4) (1973),
349-381.
DOI: https://doi.org/10.1016/0022-1236(73)90051-7
