1. K. I. BAbenko, On conjugate functions, Doklady Akad. Nauk SSSR (NS) 62 (1948)
2. S. BAnach, Thé des Opérations Linéaires, Warsaw, 1932.
3. A. Beurling, On two problems concerning linear transformations in Hilbert space, Acta Mathematica, 81 (1949), 239–255.
4. V. F. GAposkin, A generalization of a theorem of M. Riese on conjugate functions, Mat. Sbornik, 46 (88) (1958), 359–372 (Russian).
5. U. GRenander and M. ROsenblatt, Statistical Analysis of Stationary Time Series, New York, 1957.