AMSilR. “Report of Meeting: The Eleventh Katowice–Debrecen Winter Seminaron Functional Equations and Inequalities, Wisła-Malinka (Poland), February 2–5, 2011”. Annales Mathematicae Silesianae, Vol. 25, Sept. 2011, pp. 103-18, https://journals.us.edu.pl/index.php/AMSIL/article/view/14025.