Romanov, S.S. (2004) “Plane Closed Trajectories on Certain Manifolds with Rotation Metric”,
Ukrains’kyi Matematychnyi Zhurnal
, 56(2), pp. 276–283. Available at:
https://umj.imath.kiev.ua/index.php/umj/article/view/3752
(Accessed: 10 April 2025).