1. Spectral Analysis of Nonlinear Operators;Fučik,1973
2. The Theory of Compact Vector Fields and Some of Its Applications to the Topology of Functional Spaces;Granas;Rozprawy Matematyczne, No. 30,1962
3. Positive Solutions of Operator Equations;Krasnosel'skij,1964
4. Nonlinear Functional Analysis;Schwartz,1969