Broer, H. W. (2019) “A Global Kam-Theorem: Monodromy in Near-Integrable Perturbations of Spherical Pendulum”, Journal of Mathematical and Fundamental Sciences, 34(2&3), pp. 309-324. Available at: https://journals.itb.ac.id/index.php/jmfs/article/view/9268 (Accessed: 6February2026).