R. Klir, Róbert Rozenberg, Stanislav Ďurčo (2020). CELESTIAL NAVIGATION. SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 20th International Multidisciplinary Scientific GeoConference Proceedings SGEM 2020, Informatics, Geoinformatics and Remote Sensing, 311-318. https://doi.org/10.5593/sgem2020/2.2/s11.037