Burlacu I. Three-layered policy filter in free movement for work and welfare (a conceptual framework of the EU social security coordination, national social security and taxes on the welfare of frontier workers). te [Internet]. 18 czerwiec 2016 [cytowane 5 grudzień 2025];1(1):41-82. Dostępne na: https://journals.ur.edu.pl/te/article/view/8617