Zaitseva, Natalia A., Valentin S. Korneevets, Elena G. Kropinova, Tatyana Yu. Kuznetsova, and Ludmila V. Semenova. 2016. “Cross-Border Movement of People Between Russia and Poland and Their Influence on the Economy of Border Regions”. International Journal of Economics and Financial Issues 6 (4):1690-95. https://www.econjournals.com/index.php/ijefi/article/view/3156.