Petrov, Eugene, and Ihor Havrylenko. 2023. “Stability of Minimal Surfaces in the Sub-Riemannian Manifold $\widetilde{E(2)}$”. Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics 98 (December), 50-67. https://doi.org/10.26565/2221-5646-2023-98-04.