Fil , B. N., A. K. Prikarpatsky, and N. N. Pritula. 1988. “Quantum Lee Algebra of Currents Is a Universal Algebraic Structure of Symmetries of Quite Integrable Dynamic Systems”. Ukrains’kyi Matematychnyi Zhurnal 40 (6): 764-68. https://umj.imath.kiev.ua/index.php/umj/article/view/9287.