1. B. I. Golubov, A. V. Efimov, and V. A. Skvortsov, Walsh Series and Transforms: Theory and Applications (Nauka, Moscow, 1987; Kluwer, Dordrecht, 1991).
2. M. S. Bespalov, “Multiplicative Fourier Transforms,” in Function Theory and Approximation Theory: Proc. Saratov Winter School, 1982 (Sarat. Gos. Univ., Saratov, 1983), part 2, pp. 39–42 [in Russian].
3. B. I. Golubov and S. S. Volosivets, “On the Integrability and Uniform Convergence of Multiplicative Fourier Transforms,” Georgian Math. J. 16(3), 533–546 (2009).
4. M. Kinukawa, “Contractions of Fourier Coefficients and Fourier Integrals,” J. Anal. Math. 8, 377–406 (1960).
5. R. P. Boas, Jr., “Fourier Series with Positive Coefficients,” J. Math. Anal. Appl. 17(3), 463–483 (1967).