Ciukaj, Radosław, and Krzysztof Kil. “Determinants of the Non-Performing Loan Ratio in the European Union Banking Sectors With a High Level of Impaired Loans”. DEMO, vol. 6, no. 1, Mar. 2020, pp. 22-45, https://doi.org/10.18559/ebr.2020.1.2.