Grzeszczak, Robert. “Barriers to Flow of Workers Within the Internal Market – a New Approach to an Old Problem”. The Opole Studies in Administration and Law 14, no. 4 (1) (November 10, 2016): 39–54. Accessed November 2, 2024. https://czasopisma.uni.opole.pl/index.php/osap/article/view/1319.