1. J. Bergh and J. Löfström, Interpolation Spaces, Springer (Berlin, 1976.)
2. O. V. Besov, V. P. Il’in and S. M. Nikol’skij, Integral Representations of Functions and Imbedding Theorems. Vol. I, II, V. H. Winston & Sons (Washington, D.C., 1978, 1979), transalated from Russian, Scripta Series in Mathematics, Ed. by M. H. Taibleson.
3. О. В. Бесов, В. П. Ильин, и С. М. никольский, Инmегрaльные предсmaвления функцuu u mеоремы вложенuя, Изд. “Наука” (Москва, 1996).
4. V. I. Burenkov and M.L. Goldman, On the interconnection of norms of operators in periodic and nonperiodic function spaces, Trudy Mat. Inst. Steklov, 161(1983) (in Russian); translated in Proc. Steklov. Inst. Math. 3(1984) 53–112.
5. P.L. Butzer and R. Nessel, Fourier analysis and approximation, Birkhäuser (Basel, 1971).