Dokl. Akad. Nauk SSSR, 1970 Volume 193, Number 2,Pages 276–279(Mi dan35526)
MATHEMATICS
Conditions for uniform Riesz summability, of Fourier series in an arbitrary fundamental function system of Laplace's operator,
that are best possible in the classes of Solobev, Nikol'skii, Besov, Liouville and Zygmund–Hölder