LukovskyI. O., Mykhailyuk O. V., and TimokhaA. N. “On One Variational Criterion of Stability of Pseudoequilibrium Forms”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 11 (November 25, 1996): 1494-1500. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5203.