Rudenok AE, Vasilevich MN. About isochrons of strong focus. Журнал Белорусского государственного университета. Математика. Информатика [Internet]. 2025 Oct. 13 [cited 2026 Jul. 19];(2):16-29. Available from: https://journals.bsu.by/index.php/mathematics/article/view/6685