Mathematical Institute, Slovak Academy of Sciences, Štefánikova 49, 814 73 Bratislava, Slovakia
Bibliografia
[1] M. S. Berger, Nonlinearity and Functional Analysis, Academic Press, New York, 1977.
[2] S. A. Brykalov, The solvability of a nonlinear boundary value problem in a fixed set of functions, Differentsial'nye Uravneniya 27 (1991), 2027-2033 (in Russian).