Kotova, O. V., and R. M. Trigub. “A New Sufficient Condition for Belonging to the Algebra of Absolutely Convergent Fourier Integrals and Its Application to the Problems of Summability of Double Fourier Series”. *Ukrains’kyi Matematychnyi Zhurnal* 67, no. 8 (August 25, 2015): 1082-1096. Accessed September 24, 2022. http://umj.imath.kiev.ua/index.php/umj/article/view/2047.