1. A Collection of Mathematical Problems;Ulam,1960
2. On the stability of the linear functional equation;Hyers;Proceedings of the National Academy of Sciences of the United States of America,1941
3. On the stability of the linear mapping in Banach spaces;Rassias;Proceedings of the American Mathematical Society,1978
4. A generalization of the Hyers–Ulam–Rassias stability of Jensen’s equation;Lee;Journal of Mathematical Analysis and Applications,1999
5. Ulam stability of some Volterra integral equations;Lungu;Fixed Point Theory,2011