Salamaga, Marcin. “Assessing the Similarity of the Geographical Structure of Foreign Trade in the Countries of the European Union”. Krakow Review of Economics and Management Zeszyty Naukowe Uniwersytetu Ekonomicznego W Krakowie, no. 12(972), May 2018, pp. 99-112, https://doi.org/10.15678/ZNUEK.2017.0972.1207.