ASWHAD, A. A. On the Riesz Means of Expansion by Riesz Bases Formed by Eigen Functions for the Ordinary Differential Operator of 2mth Order. Ibn AL-Haitham Journal For Pure and Applied Sciences, Baghdad, Iraq., v. 23, n. 2, p. 159–167, 2017. Disponível em: https://jih.uobaghdad.edu.iq/index.php/j/article/view/1017.. Acesso em: 14 aug. 2024.