[[1] BUTZER, P. L.-BERENS, H.: Semi-Groups of Operators and Approximation. Springer- -Verlag, Berlin, 1967.10.1007/978-3-642-46066-1]Search in Google Scholar
[[2] EDWARDS, R. E.: Fourier Series I (2nd ed.), Springer-Verlag, Berlin, 1979.10.1007/978-1-4612-6208-4_8]Search in Google Scholar
[[3] EDWARDS, R. E.: Fourier Series II (2nd ed.), Springer-Verlag, Berlin, 1982.10.1007/978-1-4613-8156-3]Search in Google Scholar
[[4] KATZNELSON, Y.: An Introduction to Harmonic Analysis (2nd ed.), Dower Publications, Inc., New York, 1976.]Search in Google Scholar
[[5] SHILOV, G. E.: Homogeneous rings of functions, Usp. Mat. Nauk n. Ser. 6 53 (1951), no. 1, 91-137, (In Russian).]Search in Google Scholar
[[6] SHILOV, G. E.: Homogeneous rings of functions, Amer. Math. Soc., Transl. 92 (1953), 392-453.]Search in Google Scholar
[[7] SHILOV, G. E.: Mathematical Analysis, Fizmatgiz, Moscow 1961. (In Russian)]Search in Google Scholar