Aouf, M. K., A. O. Mostafa, and H. M. Zayed. “Mapping Properties for Convolution involving hypergeometric Series”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 70, no. 11, Nov. 2018, pp. 1466-75, https://umj.imath.kiev.ua/index.php/umj/article/view/1650.