“Non-Classical Elliptic Projections and $L^2$-Error Estimates for Galerkin Methods for Parabolic Integro-Differential Equations”. Journal of Computational Mathematics 9, no. 3 (September 1, 1991): 238–246. Accessed December 5, 2025. https://www.global-sci.com/index.php/JCM/article/view/11033.