Parameswaran, M. R. “On the Translativity of Hausdorff and Some Related Methods of Summability”. The Journal of the Indian Mathematical Society 23, no. 1-2 (June 1, 1959): 45–64. Accessed April 29, 2024. https://www.informaticsjournals.com/index.php/jims/article/view/16919.