Younis, M. S. “On Strong Approximation of Fourier Series”. Anal. Numér. Théor. Approx. 16, no. 1 (February 1, 1987): 87–91. Accessed November 22, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1987-vol16-no1-art14.