1. D. Waterman, “On Convergence of Fourier Series of Functions of Generalized Bounded Variation,” Stud. math. 44(1), 107 (1972).
2. A. A. Saakyan, “Convergence of Double Fourier Series of Functions of Bounded Harmonic Variation,” Izv. Akad. Nauk Arm. SSR 21(6), 517 (1986).
3. A. I. Sablin, “Λ-Variation and Fourier Series,” Izv. Vuzov. Matem. No. 10, 66 (1987).
4. A. N. Bakhvalov, “Continuity in Λ-Variation of Functions of Several Variables and Convergence of Multiple Fourier Series,” Matem. Sbornik 193(12), 3 (2002) [Sbornik: Math. 193 (12), 1731 (2002)].
5. D. Waterman “On the Summability of Fourier Series of Functions of Λ-Bounded Variation,” Stud. math. 55(1), 87 (1976).