On the functional equation $f(x) + ∑_{i = 1}^n g_i(y_i) = h(T(x, y_1, y_2,...,y_n))$
Volume 27 / 1973
Annales Polonici Mathematici 27 (1973), 329-336
DOI: 10.4064/ap-27-3-329-336