“Bifurcation of coisotropic invariant tori under locally Hamiltonian perturbations of integrable systems and nondegenerate deformations of the symplectic structure” (2006) Neliniini Kolyvannya, 9(2), pp. 221–232. Available at: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/393 (Accessed: 21 January 2026).