1. K. I. Babenko, ?On certain problems of approximation theory and numerical analysis,? Usp. Mat. Nauk,40, No. 1, 3?27 (1985).
2. F. Riesz and B. Sz. Nagy, Lectures on Functional Analysis [Russian translation], Mir, Moscow (1979).
3. A. Pietsch, Operator Ideals, North-Holland, Amsterdam (1980).
4. V. N. Temlyakov, ?On the approximation of periodic functions of several variables,? Dokl. Akad. Nauk SSSR,279, No. 2, 301?305 (1984).
5. S. Heinrich, On the Optimal Error of Degenerate Kernel Methods, Forchungsergebnisse-Freidrich-Schiller-Universität Jena, No. 84/2 (1984).