Mamrai, Vita. “ACTIVITIES OF THE ALL-UKRAINIAN NETWORK OF THE OBSERVATION POINTS (1920’S – 1930’S)”. Scientific Journal of Polonia University 42, no. 5 (February 12, 2021): 142-148. Accessed April 27, 2024. http://pnap.ap.edu.pl/index.php/pnap/article/view/604.