ENGEL O, SZÁSZ R. On a subclass of convex functions. Stud. Univ. Babeş-Bolyai Math. [Internet]. 2016 Jun. 30 [cited 2025 Apr. 25];61(2):137-46. Available from: https://studia.reviste.ubbcluj.ro/index.php/subbmathematica/article/view/5540