ParasyukI. O. (1993) “Variables of the action-angle type on symplectic manifolds stratified by coisotropic tori”, Ukrains’kyi Matematychnyi Zhurnal, 45(1), pp. 77–85. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5785 (Accessed: 6October2024).