1. Browder, F. E.: Nonexpansive nonlinear operators in a Banach space. Proc. Nat. Acad. Sci. USA54, 1041?1043 (1965).
2. Darbo, G.: Punti uniti in trasformazioni a condominio non compatto. Rend. Sem. Mat. Univ. Padova24, 84?92 (1955).
3. Edmunds, D. E.: Remarks on nonlinear functional equations. Math. Ann.174, 233?239 (1967).
4. Krasnoselski, M. A.: Zwei Bemerkungen über die Methode der sukzessiven Approximationen. Uspehi Mat. Nauk10, No 1 (63), 123?127 (1955).
5. ?, Kachurovski, R. I.: On a fixed-point theorem for operators in Hilbert space. Function analiz i prilozen1, 93?94 (1967).