1. J. P. Aubin, Nonlinear stability-approximatiomof nonlinear operational equations (to appear).
2. F. E. Browder, On the solvability of nonlinear functional equations, Duke Math. J. 39 (1963), 557–566.
3. ——, Remarks on nonlinear functional equations II, Illinois J. Math. 7 (1965), 608–618.
4. ——, Nonlinear accretive operators in Banach space (to appear).
5. ——, Approximation-solvability of nonlinear functional equations in normed linear spaces (to appear in Archive Rat. Mech. Anal.).