[1] G. Bonanno and G. Molica Bisci, Infinitely many solutions for a boundary value problem with discontinuous nonlinearities, Bound. Value Probl., (2009), Art. ID 670675, 20pp.
[2] M. Belloni, V. Ferone and B. Kawohl, Isoperimetric inequalities, Wulff shape and related questions for strongly nonlinear elliptic operators, Z. Angew. Math. Phys., 54 (2003), 771-783. doi: 10.1007/s00033-003-3209-y.
[3] F. Della Pietra and N. Gavitone, Anisotropic elliptic problems involving Hardy-type potential, J. Math. Anal. Appl., 397 (2013), 800-813. doi: 10.1016/j.jmaa.2012.08.008.
[4] G. Dinca, P. Jebelean and J. Mawhin, Variational and topological methods for Dirichlet problems with pp-Laplacian, Port. Math. (N.S.), 58 (2001), 339-378.
[5] J. Diestel, Geometry of Banach Spaces – Selected Topics, Lecture Notes in Mathematics, Vol. 485. Springer-Verlag, Berlin-New York, 1975.
[6] I. Ekeland, Nonconvex minimization problems, Bull. Amer. Math. Soc. (N.S.), 1 (1979), 443-474. doi: 10.1090/S0273-0979-1979-14595-6.
[7] F. Faraci and A. Kristály, One-dimensional scalar field equations involving an oscillatory nonlinear term, Discrete Contin. Dyn. Syst., 18 (2007), 107-120. doi: 10.3934/dcds.2007.18.107.
[8] V. Ferone and B. Kawohl, Remarks on a Finsler-Laplacian, Proc. Amer. Math. Soc., 137 (2009), 247-253. doi: 10.1090/S0002-9939-08-09554-3.
[9] M. Frigon, On a new notion of linking and application to elliptic problems at resonance, J. Differential Equations, 153 (1999), 96-120. doi: 10.1006/jdeq.1998.3540.
[10] N. Ghoussoub and D. Preiss, A general mountain pass principle for locating and classifying critical points, Ann. Inst. H. Poincaré Anal. Non Linéaire, 6 (1989), 321-330.
[11] R. Glowinski and A. Marrocco, Sur l’approximation par éléments finis d’ordre un et la resolution par penalisation-dualité d’une classe de problemes de Dirichlet non linéaires, Rev. Française Automat. Informat. Recherche Opérationnelle Sér. Rouge Anal. Numér., 9 (1975), 41-76.
[12] D. Guo, J. Sun and G. Qi, Some extensions of the mountain pass lemma, Differential Integral Equations, 1 (1988), 351-358
[13] M. A. Krasnoselskii, Positive Solutions of Operator Equations, Translated from the Russian by Richard E. Flaherty; edited by Leo F. Boron, P. Noordhoff Ltd., Groningen 1964.
[14] A. Kristály, Infinitely many solutions for a differential inclusion problem in RN, J. Differential Equations, 220 (2006), 511-530. doi: 10.1016/j.jde.2005.02.007.
[15] L. Ma, Mountain pass on a closed convex set, J. Math. Anal. Appl., 205 (1997), 531-536. doi: 10.1006/jmaa.1997.5227.
[16] S. A. Marano and D. Motreanu, Infinitely many critical points of non-differentiable functions and applications to a Neumann-type problem involving the pp-Laplacian, J. Differential Equations, 182 (2002), 108-120. doi: 10.1006/jdeq.2001.4092.
[17] M. Marcus and V. Mizel, Every superposition operator mapping one Sobolev space into another is continuous, J. Funct. Anal., 33 (1979), 217-229. doi: 10.1016/0022-1236(79)90113-7.
[18] R. Precup, The Leray-Schauder boundary condition in critical point theory, Nonlinear Anal., 71 (2009), 3218-3228. doi: 10.1016/j.na.2009.01.195.
[19] R. Precup, On a bounded critical point theorem of Schechter, Stud. Univ. Babeş-Bolyai Math., 58 (2013), 87-95.
[20] R. Precup, Critical point localization theorems via Ekeland’s variational principle, Dynam. Systems Appl., 22 (2013), 355-370.
[21] P. Pucci and J. Serrin, A mountain pass theorem, J. Differential Equations, 60 (1985), 142-149. doi: 10.1016/0022-0396(85)90125-1.
[22] B. Ricceri, A general variational principle and some of its applications, J. Comput. Appl. Math., 113 (2000), 401-410. doi: 10.1016/S0377-0427(99)00269-1.
[23] B. Ricceri, Infinitely many solutions of the Neumann problem for elliptic equations involving the pp-Laplacian, Bull. London Math. Soc., 33 (2001), 331-340. doi: 10.1017/S0024609301008001.
[24] J. Saint Raymond, On the multiplicity of solutions of the equation ),−Δu=λf(u), −Δu=λf(u), J. Differential Equations, 180 (2002), 65-88. doi: 10.1006/jdeq.2001.4057.
[25] M. Schechter, A bounded mountain pass lemma without the (PS) condition and applications, Trans. Amer. Math. Soc., 331 (1992), 681-703. doi: 10.1090/S0002-9947-1992-1064270-1.
[26] M. Schechter, Linking Methods in Critical Point Theory, Birkhäuser, Boston, 1999. doi: 10.1007/978-1-4612-1596-7