1. N. A. Davydov, ?Conservative positive matrix summation methods ineffective on classes of sequences,? Ukr. Mat. Zh.,32, No. 2, 155?159 (1980).
2. G. A. Mikhailin, ?Ineffectiveness of one class of regular matrices,? Mat. Zametki,16, No. 3, 361?364 (1974).
3. G. Hardy, Divergent Series, Oxford, Great Britain (1949).
4. R. Cooke, Infinite Matrices and Spaces of Sequences [Russian translation], Fizmatgiz, Moscow (1960).
5. K. Zeller, ?Allgemeine Eigenschaften von Limitierungsverfahren,? Math. Zeit.,53, 463?487 (1951).