On Hyers-Ulam stability of a special case of O'Connor's and Gajda's functional equations. Bouikhalene, Belaid; Elqorachi, Elhoucien; Redouani, Ahmed — 2005 JIPAM. Journal of Inequalities in Pure & Applied Mathematics [electronic only]
Hyers-Ulam stability of the generalized trigonometric formulas. Redouani, Ahmed; Elqorachi, Elhoucien; Bouikhalene, Belaid — 2006 JIPAM. Journal of Inequalities in Pure & Applied Mathematics [electronic only]
Hyers-Ulam stability of the generalized quadratic functional equation in amenable semigroup. Bouikhalene, Belaid; Elqorachi, Elhoucien; Redouani, Ahmed — 2007 JIPAM. Journal of Inequalities in Pure & Applied Mathematics [electronic only]