1. W. Rudin,Fourier analysis on groups, Interscience (New York, 1962).
2. N. Ja. Vilenkin, On a class of complete orthogonal systems,Izv. Akad. Nauk SSSR, Ser. Mat.,11 (1947), 363–400; English Transl.,Amer. Math. Soc. Trans. Ser. 2.,28(1963), 1–35.
3. W. R. Wade, Sets of uniqueness for the group of integers of ap-series field,Canad. J. Math.,31 (1979), 858–866.
4. K. Yoneda, Perfect sets of uniqueness on the group 2 ω ,Canad. J. Math.,34 (1982), 759–764.
5. A. Zygmund,Trigonometric series, Cambridge Univ. Press (Cambridge, 1959).