[1] Aguinaldo L., Schmitt K.: On the boundary value problem $u" + u = au^- + p(t), u(0) = 0 = u(\pi)$. Proc. Amer. Math. Soc. 68 (1978), 64-68. MR 0466707

[2] Ahmad S.: A resonance problem in which the nonlineariiy may grow linearly. Proc. Amer. Mat. Soc. 82 (1984), 381-384. MR 0759657

[3] Brezis H.: Periodic solutions of nonlinear vibrating strings and duality principles. Bull. Amer. Math. Soc. 8 (1983), 409-426. MR 0693957 | Zbl 0537.35055

[4] Cesari L., Kannan R.: An abstract theorem at resonance. Proc. Amer. Math. Soc. 63 (1977), 221-225. MR 0448180

[5] Cesari L., Kannan R.: Existence of solutions of a nonlinear differential equation. Proc. Amer. Math. Soc. 88 (1983), 605-613. MR 0702284 | Zbl 0529.34005

[6] Drábek P.: On the resonance problem with nonlinearity which has arbitrary linear growth. J. Math. Anal. Appl. 127 (1987), 435-442. MR 0915069

[7] Fučík S.: Boundary value problems with jumping nonlinearities. Časopis Pěst. Mat. 101 (1976), 69-87. MR 0447688

[8] Iaanaci R., Nkashama M.N., Ward J.R.: Nonlinear second order elliptic partial differential equations at resonance. Trans. Amer. Math. Soc. 311 (1989), 711-726. MR 0951886

[9] Kannan R., Ortega R.: Existence of solutions of $x'' + x + g(x) = p(t), x(0) = 0 = x(\pi)$. Proc. Amer. Math. Soc. 96 (1986), 67-70. MR 0813812 | Zbl 0585.34001

[10] Kannan R., Lakshmikantham V., Nieto J. J.: Sufficient conditions for existence of solutions of nonlinear boundary value problems at resonance. Nonlinear Anal. 7 (1983), 1013-1020. MR 0713210 | Zbl 0542.47053

[11] Kannan R., Nieto J. J., Ray M. B.: A class of nonlinear boundary value problems without Landesman-Lazer condition. J. Math. Anal. Appl. 105 (1985), 1-11. MR 0773569 | Zbl 0589.34013

[12] Nieto J. J.: Hukuhara-Kneser property for a nonlinear Dirichlet problem. J. Math. Anal. Appl. 128 (1987), 57-63. MR 0915966 | Zbl 0648.34019

[13] Nieto J. J.: Aronszajn's theorem for some nonlinear Dirichlet problems with unbounded nonlinearities. Proc. Edinburgh Math. Soc. 31 (1988), 345-351. MR 0969064 | Zbl 0631.34027

[14] Schechter M., Shapiro J., Snow M.: Solutions of the nonlinear problem $Au = Nu$ in a Banach space. Trans. Amer. Math. Soc. 241 (1978), 69-78. MR 0492290