“…They find application in various contexts, including functional equations, and often emerge as subdifferentials of convex functions in the field of calculus of variations (see, for example, Pascali and Sburian [39] and Rockafellar [41, page 101]). For the solution of the zeros of A, see Mendy et al [ [5], [3], [9], [7], [8], [31]].…”