[1]
S. S. Romanov, “Plane Closed Trajectories on Certain Manifolds with Rotation Metric”, Ukr. Mat. Zhurn., vol. 56, no. 2, pp. 276–283, Feb. 2004, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3752