On approximate solutions of a functional equation in the class of differentiable functions Kazimierz Dankiewicz — 1989 Annales Polonici Mathematici
On continuous solutions of a functional equation Kazimierz Dankiewicz — 1997 Annales Polonici Mathematici This paper discusses continuous solutions of the functional equation φ[f(x)] = g(x,φ(x)) in topological spaces.