Ligun, A.A. and Shumeiko, A.A. (1997) “On one problem of minimization of area”, Ukrains’kyi Matematychnyi Zhurnal, 49(7), pp. 927–936. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5083 (Accessed: 5 December 2025).