Луппо, О. Є., and Я. А. Пігур. “Definition of Indicators to Assess the Operational Safety and Environment Definition of the Elements of Air Navigation Systems”. Proceedings of National Aviation University 55, no. 2 (May 11, 2013): 27–32. Accessed May 1, 2024. https://jrnl.nau.edu.ua/index.php/visnik/article/view/5404.