1. Bochner, S. “Boudary Values of Analytic Functions of Several Variables and of Almost Periodic Functions,” Ann. Math. 45, No. 4, 708–722 (1944).
2. Rudin, W. Function Theory in Polydiscs (W. A. Benjamin, Inc., New York, 1969; Mir, Moscow, 1974).
3. Storozhenko, E. A. “Approximation of Functions of Class H p, 0 < p ≤ 1,” Mat. Sb. 105, No. 4, 601–621 (1978).
4. Volashek, Ya. “Approximation in Multi-Dimensional Hardy Spaces H p, 0 < p ≤ 1,” Soobshch. Akad. Nauk GSSR 105, No. 1, 21–24 (1982).
5. Weisz, F. “Cesàro-Summability of Higher-Dimensional Fourier Series,” Ann. Univ. Sci. Budapest, Sect. Comp. 37, 47–64 (2012).