Altinkaya, S., Kanas, S., & Yal¸cin, S. (2018). Subclass of $k$-uniformly starlike functions defined by symmetric $q$-derivative operator. Ukrains’kyi Matematychnyi Zhurnal, 70(11), 1499-1510. https://umj.imath.kiev.ua/index.php/umj/article/view/1653