Parasyuk, I.O. (1994) “Reduction and coisotropic invariant tori of Hamiltonian systems with non-poisson commutative symmetries. I”,
Ukrains’kyi Matematychnyi Zhurnal, 46(5), pp. 537–544. Available at:
https://umj.imath.kiev.ua/index.php/umj/article/view/5717 (Accessed: 10 April 2025).