O. J. B. Almeida Pereira and J. P. Moitinho de Almeida, “Adaptive refinement for a local error bound based on duality”, Comp. Assist. Methods Eng. Sci., vol. 10, no. 4, pp. 565–574, Jan. 2023, Accessed: Jun. 30, 2025. [Online]. Available: https://cames.ippt.pan.pl/index.php/cames/article/view/1065