CZERSKI, R.; KUSTRA, M.; GONIEWICZ, K. A flexible response of NATO to potential threats occurring on the eastern border. Journal of Education, Health and Sport, [S. l.], v. 9, n. 5, p. 107–112, 2019. Disponível em: https://apcz.umk.pl/JEHS/article/view/6891. Acesso em: 2 dec. 2023.