1. N. K. Bari, Trigonometric Series (Fizmatgiz, Moscow, 1961; Pergamon Press Book, The Macmillan Co., New York, 1964).
2. J.M. Ash and G. V. Welland, “Convergence, Uniqueness, and Summability of Multiple Trigonometric Series,” Trans. Amer. Math. Soc. 163(2), 401–436 (1972).
3. G. E. Reves and O. Szasz, “Some Theorems on Double Trigonometric Series,” Duke Math. J. 9(4), 693–705 (1942).
4. P. J. Cohen, “Topics in the Theory of Uniqueness of Trigonometrical Series,” Thesis (University of Chicago, Chicago, Il., 1958).
5. J.M. Ash and G. Wang, “One and Two Dimensional Cantor-Lebesgue Type Theorems,” Trans. Amer. Math. Soc. 349(4), 1663–1674 (1997).