TONOYAN, L. G. ON THE SOME EXTREMAL PROBLEM. Proceedings of the YSU A: Physical and Mathematical Sciences, Yerevan, Armenia, v. 36, n. 3 (199), p. 7–11, 2002. DOI: 10.46991/PYSUA.2002.36.3.007. Disponível em: https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol36_no3_2002_pp007-011. Acesso em: 22 jan. 2026.