[1] BERGER M. S.: Nonlinearity and Functional Analysis. Academic Press, New York, 1977. MR 0488101 | Zbl 0368.47001

[2] BERKOVITS J.-MUSTONEN V.: An extension of Leray-Schauder degree and applications to nonlinear wave equations. Differential Integral Equations 3 (1990), 945-963. MR 1059342 | Zbl 0724.47024

[3] BIELAWSKI R.-GORNIEWICZ L.: A fixed point index approach to some differential equations. In: Proc. Conf. Topological Fixed Point Theory and Appl. (Boju Jiang, Ed.). Lecture Notes in Math. 1411, Springer-Verlag, New York, 1989, pp. 9-14. MR 1031778 | Zbl 0685.55001

[4] DEIMLING K.: Nonlinear Functional Analysis. Springer-Verlag, Berlin, 1985. MR 0787404 | Zbl 0559.47040

[5] ERBE L. H.-KRAWCEWICZ W.-KACZYNSKI T.: Solvability of two-point boundary value problems for systems of nonlinear differential equations of the form y" = 9(t,y,y'>y"). Rocky Mountain J. Math. 20 (1990), 899-907. MR 1096559

[6] FEČKAN M.: Nonnegative solutions of nonlinear integral equations. Comment. Math. Univ. Carolin. 36 (1995), 615-627. MR 1378685 | Zbl 0840.45007

[7] FEČKAN M.: On the existence of solutions of nonlinear equations. Proc. Amer. Math. Soc. 124 (1996), 1733-1742. MR 1327010 | Zbl 0861.47045

[8] FRIGON M.-KACZYNSKI T.: Boundary value problems for systems of implicit differential equations. J. Math. Anal. Appl. 179 (1993), 317-326. MR 1249822 | Zbl 0799.34023

[9] PETRYSHYN W. V.: Solvability of various boundary value problems for the equation x" = f(t,x,x',xn) - y. Pacific J. Math. 122 (1986), 169-195. MR 0825230

[10] PETRYSHYN W. V.-YU Z. S.: On the solvability of an equation describing the periodic motions of a satellite in its elliptic orbit. Nonlinear Anal. 9 (1985), 969-975. MR 0804562 | Zbl 0581.70024

[11] PETRYSHYNW V.-YU Z. S.: Solvability of Neumann bv problems for nonlinear second-order odes which need not be solvable for the highest-order derivative. J. Math. Anal. Appl. 91 (1983), 244-253. MR 0688543

[12] RICCERI B.: On the Cauchy problem for the differential equation f(t,x,x',\ldots, x^{(k)}) = 0$. Glasgow Math. J. 33 (1991), 343-348. MR 1127526

[13] SCHNEIDER K. R.: Existence and approximation results to the Cauchy problem for a class of differential-algebraic equations. Z. Anal. Anwendungen 10 (1991), 375-384. MR 1155617 | Zbl 0772.34003

[14] WEBB J. R. L.-WELSH S. C.: Existence and uniqueness of initial value problems for a class of second-order differential equations. J. Differential Equations 82 (1989), 314-321. MR 1027971 | Zbl 0691.34005