1. Baron, K.,On approximate solutions of a functional equation. Bull. Acad. Polon. Sci. Sér. Sci. Math. Astronom. Phys.23 (1975), 1065–1068.
2. Baron, K.,On extending solutions of a functional equation. Aequationes Math.13 (1975), 285–288.
3. Baron, K.,Functional equations of infinite order. Prace Nauk. Uniw. Sl⇂sk. w Katowicach (Scientific Publications of the University of Silesia)265, Uniw. Śl⇂ski, Katowice, 1978.
4. International Series of Numerical Mathematics;K. Baron,1980
5. Baron, K.,On approximate solutions of a system of functional equations. To appear in Ann. Polon. Math.