Ersteniuk Y, Gasyuk I, Boryschak A, Yakubovskyi P. Methodology of Problems Creation and Selection for Astronomy Olympiads on Example of Tasks on the Topic of Kepler’s Laws . jpnu [Internet]. 2020 Apr. 21 [cited 2024 Apr. 20];7(1):156-65. Available from: https://journals.pnu.edu.ua/index.php/jpnu/article/view/3629