Bitimkhan, S. “Generalization of the Hardy-Littlewood Theorem on Fourier Series”. Bulletin of the Karaganda University. Mathematics Series 104, no. 4 (December 30, 2021): 49–55. Accessed July 8, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/462.