Mach A, Moszner Z. Unstable (Stable) system of stable (unstable) functional equations. Ann. Univ. Paedagog. Crac. Stud. Math. [Internet]. 2010 Mar. 12 [cited 2026 Oct. 30];9:43-8. Available from: https://studmath.uken.krakow.pl/article/view/13244