Bettiol P, Mariconda C. The basic problem of the calculus of variations: Du Bois-Reymond equation, regularity of minimizers and of minimizing sequences. BPMAS [Internet]. 2022 Jan. 1 [cited 2024 Dec. 3];13(1):26-43. Available from: https://mathematicalanalysis.unibo.it/article/view/16156