1. H.Brezis - L.Nirenberg,Characterization of the range of some nonlinear operators and applications to boundary value problems, Annali Scuola Normale Sup. Pisa, to appear.
2. M.Furi - M.Martelli - A.Vignoli,Contributions to the spectral theory for nonlinear operators in Banach spaces, to appear in Ann. di Mat. pura e appl.
3. R. E.Gaines - J. L.Mawhin,Coincidence degree, and nonlinear differential equations, Lecture Notes in Math. 568, Springer-Verlag, 1977.
4. A. Granas,The theory of compact vector fields and some applications to the theory of functional spaces, Rozprawy Matematyczne, Warszawa,30 (1962).
5. J. L. Mawhin,Equivalence theorems for nonlinear operator equations and coincidence degree for some mappings in locally convex topological vector spaces, J. Diff. Eq.,12 (1972), pp. 610–636.