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 . Journal of Vasyl Stefanyk Precarpathian National University, v. 7, n. 1, p. 156-165, 21 Apr. 2020.