[1] R. Bartnik and L. Simon, ‘Spacelike hypersurfaces with prescribed boundary values and mean curvature’, Comm. Math. Phys. 87 (1982–83) 131–152.
[2] C. Bereanu, P. Jebelean and J. Mawhin, ‘Radial solutions for some nonlinear problems involving mean curvature operators in Euclidean and Minkowski spaces’, Proc. Amer. Math. Soc. 137 (2009) 161–169.
[3] C. Bereanu and J. Mawhin, ‘Existence and multiplicity results for some nonlinear problems with singular φ-Laplacian’, J. Differential Equations 243 (2007) 536–557.
[4] C. Bereanu and J. Mawhin, ‘Boundary value problems for some nonlinear systems with singular φ-laplacian’, J. Fixed Point Theory Appl. 4 (2008) 57–75.
[5] C. Bereanu and J. Mawhin, ‘Nonhomogeneous boundary value problems for some nonlinear equations with singular φ-Laplacian’, J. Math. Anal. Appl. 352 (2009) 218–233.
[6] I. Coelho, C. Corsato, F. Obersnel and P. Omari, ‘Positive solutions of the Dirichlet problem for the one-dimensional Minkowski-curvature equation’, Adv. Nonlinear Stud. 12 (2012) 621–638.
[7] C. De Coster and P. Habets, Two-point boundary value problems: lower and upper solutions (Elsevier, Amsterdam, 2006).
[8] C. Gerhardt, ‘H-surfaces in Lorentzian manifolds’, Comm. Math. Phys. 89 (1983) 523–553.
[9] A. Granas and J. Dugundji, Fixed point theory (Springer, New York, 2003).
[10] D.-R. Herlea, ‘Positive solutions for second-order boundary-value problems with φ-Laplacian’, Electron. J. Differential Equations 2016 (2016) 1–8.
[11] P. Jebelean, J. Mawhin and C. S¸erban, ‘Multiple periodic solutions for perturbed relativistic pendulum systems’, Proc. Amer Math. Soc. 143 (2015) 3029–3039.
[12] P. Jebelean and C. S¸erban, ‘Boundary value problems for discontinuous perturbations of singular φ-Laplacian operator’, J. Math. Anal. Appl. 431 (2015) 662–681.
[13] J. L. W. V. Jensen, ‘Sur les fonctions convexes et les in´egalit´es entre les valeurs moyennes’, Acta Math. 30 (1906) 175–193.
[14] M. A. Krasnoselskii, Positive solutions of operator equations (Noordhoff, Groningen, 1964).
[15] H. Lisei, R. Precup and C. Varga, ‘A Schechter type critical point result in annular conical domains of a Banach space and applications’, Discrete Contin. Dyn. Syst. 36 (2016) 3775–3789.
[16] A. Capietto, P. Kloeden, J. Mawhin, S. Novo and M. Ortega ‘Resonance problems for some non-autonomous ordinary differential equations’, Stability and bifurcation theory for non-autonomous differential equations, Lecture Notes in Mathematics 2065 (eds R. Johnson and M. P. Pera; Springer, Berlin, Heidelberg, 2013) 103–184.
[17] R. Precup, ‘Positive solutions of semi-linear elliptic problems via Krasnoselskii type theorems in cones and Harnack’s inequality’, AIP Conf. Proc. 835 (2006) 125–132.
[18] R. Precup, ‘Critical point theorems in cones and multiple positive solutions of elliptic problems’, Nonlinear Anal. 75 (2012) 834–851.
[19] R. Precup, ‘Critical point localization theorems via Ekeland’s variational principle’, Dynam. Systems Appl. 22 (2013) 355–370.
[20] A. W. Roberts and D. E. Varberg, Convex functions (Academic Press, New York, 1973).
[21] M. Schechter, Linking methods in critical point theory (Birkh¨auser, Boston, 1999).