N. S. Chernikov, “On finite solvable groups decomposable into the product of two nilpotent subgroups”, Ukr. Mat. Zhurn., vol. 52, no. 6, pp. 809–819, Jun. 2000, Accessed: Dec. 05, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4475