1. Konyushkov A. A., “Best approximations by trigonometric polynomials and Fourier coefficients,” Mat. Sb., vol. 44, no. 1, 53–84 (1958).
2. Ulyanov P. L., “Absolute and uniform convergence of Fourier series,” Math. USSR-Sb., vol. 1, no. 2, 169–197 (1967).
3. Andrienko V. A., “The imbedding of certain classes of functions,” Math. USSR-Izv. Akad. Nauk SSSR Ser. Mat., vol. 1, no. 6, 1255–1270 (1967).
4. Ulyanov P. L., “The imbedding of certain function classes $ H_{p}^{\omega} $,” Math. USSR-Izv. Akad. Nauk SSSR Ser. Mat., vol. 2, no. 3, 601–637 (1968).
5. Ulyanov P. L., “Imbedding theorems and relations between best approximations (moduli of continuity) in different metrics,” Math. USSR-Sb., vol. 10, no. 1, 103–126 (1970).