Khomenko О. M. “α-Primitive Elements in the Generalized Verma Modules”.
Ukrains’kyi Matematychnyi Zhurnal
52, no. 8 (August 25, 2000): 1135–1140. Accessed April 11, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/4518
.