Volosivets С., and Golubov Б. “Hardy and Hardy-Littlewood Fractional Modified Operators in the Hertz and Morrey-Hertz Spaces”. BULLETIN OF THE L.N. GUMILYOV EURASIAN NATIONAL UNIVERSITY. Mathematics. Computer Science. Mechanics Series, vol. 123, no. 2, June 2018, pp. 66-70, https://bulmathmc.enu.kz/index.php/main/article/view/23.