Akturk, S., and A. Ashyralyev. “The Structure of Fractional Spaces Generated by the Two-dimensional difference Operator on the Half Plane”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 70, no. 8, Aug. 2018, pp. 1019-32, http://umj.imath.kiev.ua/index.php/umj/article/view/1614.