1.
Popovych D. A contraction between Lie algebras with necessarily singular components of the contraction matrix . Dopov. Nac. akad. nauk Ukr. [Internet]. 2014 Jul. 28 [cited 2026 Jun. 20];(7):29-35. Available from: https://nasu-periodicals.org.ua/index.php/dp/article/view/16578