The aim of this paper is to show the equivalence of two classes of nonsmooth functions. We also compare optimality conditions which have been stated for these classes.
"Relation Between the Class of M. Sama and the Class of $\ell$-stable Functions." Taiwanese J. Math. 21 (5) 1161 - 1174, October, 2017. https://doi.org/10.11650/tjm/7124