STEIN, Erwin. Milestones of Direct Variational Calculus and its Analysis from the 17th Century until today and beyond – Mathematics meets Mechanics – with restriction to linear elasticity. Computer Assisted Methods in Engineering and Science, [S.l.], v. 25, n. 4, p. 141-225, july 2019. ISSN 2299-3649. Available at: <https://cames.ippt.pan.pl/index.php/cames/article/view/256>. Date accessed: 03 dec. 2020.