Valkov, Iliya. “Methodologies for Measuring Media Freedom. The Bulgarian Case (Comparative Analysis of the Methodologies Used by Freedom House, Reporters Without Borders, CMPF, IREX, and AEJ-Bulgaria)”. UNWE Yearbook, no. 1, Feb. 2021, pp. 139-65, https://bjiep.e-dnrs.org/index.php/yb/article/view/5949.