[[1] Badora R., Przebieracz B., Volkmann P., Stability of the Pexider functional equation, Ann. Math. Sil. 24 (2010), 7-13.]Search in Google Scholar
[[2] Badora R., Przebieracz B., Volkmann P., On Tabor groupoids and stability of some functional equations, Aequationes Math. 87 (2014), 165-171.10.1007/s00010-013-0206-x]Search in Google Scholar
[[3] Forti G.L., Remark 11 (at the 22nd International Symposium on Functional Equations, Oberwolfach 1984), Aequationes Math. 29 (1985), 90-91.10.1007/BF02189806]Search in Google Scholar
[[4] Lifšic E.A., Ideal’no vypuklye množestva, Funkcional’. Analiz Priložen. 4 (1970), no. 4, 76-77.]Search in Google Scholar
[[5] Moszner Z., On the stability of functional equations, Aequationes Math. 77 (2009), 33-88.10.1007/s00010-008-2945-7]Search in Google Scholar
[[6] Páles Z., Volkmann P., Luce R.D., Hyers-Ulam stability of functional equations with a square-symmetric operation, Proc. Nat. Acad. Sci. U.S.A. 95 (1998), 12772-12775.10.1073/pnas.95.22.12772235839788988]Search in Google Scholar
[[7] Rätz J., On approximately additive mappings, in: General inequalities 2, International Series of Numerical Mathematics 47, Birkhäuser, Basel, 1980, pp. 233-251.10.1007/978-3-0348-6324-7_22]Search in Google Scholar
[[8] Tabor Jacek, Ideally convex sets and Hyers theorem, Funkcial. Ekvac. 43 (2000), 121-125.]Search in Google Scholar
[[9] Tabor Józef, Remark 18 (at the 22nd International Symposium on Functional Equations, Oberwolfach 1984), Aequationes Math. 29 (1985), 96.]Search in Google Scholar
[[10] Toborg I., Tabor groups with finiteness conditions, Aequationes Math. 90 (2016), 699-704.10.1007/s00010-015-0369-8]Search in Google Scholar
[[11] Volkmann P., Zur Rolle der ideal konvexen Mengen bei der Stabilität der Cauchyschen Funktionalgleichung, Sem. LV, no. 6 (1999), 6 pp., http://www.math.us.edu.pl/smdk]Search in Google Scholar
[[12] Volkmann P., O stabilnosci równan funkcyjnych o jednej zmiennej, Sem. LV, no. 11 (2001), 6 pp., Errata ibid. no. 11bis (2003), 1 p., http://www.math.us.edu.pl/smdk]Search in Google Scholar