Risteska, A., and M. Kocaleva Vitanova. “APPLICATION OF FUNDAMENTAL LEMMA OF VARIATIONAL CALCULUS TO THE PROBLEM OF PLATEAU”. Balkan Journal of Applied Mathematics and Informatics, Vol. 6, no. 1, June 2023, pp. 17-24, https://js.ugd.edu.mk/index.php/bjami/article/view/5646.