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://www.jih.uobaghdad.edu.iq/index.php/j/article/view/1017. Acesso em: 1 may. 2025.