PetravchukA. P. “On Strongly Inert Subalgebras of an Infinite-Dimensional Lie Algebra”. Ukrains’kyi Matematychnyi Zhurnal 54, no. 7 (July 25, 2002): 1025-1028. Accessed November 22, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4143.