1. Bari NK, Stečkin SB: Best approximation and differential properties of two conjugate functions. Tr. Mosk. Mat. Obŝ. 1956, 5: 483–522. (in Russian)
2. Flett TM: On an extension of absolute summability and some theorems of Littlewood and Paley. Proc. Lond. Math. Soc. 1957, 7: 113–141.
3. Bor H: An application of almost increasing sequences. Math. Inequal. Appl. 2002, 5(1):79–83.
4. Bor H, Srivastava HM: Almost increasing sequences and their applications. Int. J. Pure Appl. Math. 2002, 3: 29–35.
5. Bor H: A study on almost increasing sequences. JIPAM. J. Inequal. Pure Appl. Math. 2003., 4(5): Article ID 97