Díez, P. ., I. . Morata, and A. . Huerta. “Goal-Oriented Adaptivity for Shell Structures: Error Assessment and Remeshing Criteria”. European Journal of Computational Mechanics, vol. 12, no. 6, June 2003, pp. 691-15, https://journals.riverpublishers.com/index.php/EJCM/article/view/2407.