Atanasov, Atanas, and Todor Kaloyanov. “Methodological Approaches of Sampling Surveys for Examining the Beneficiaries of OP HRD 2014-2020”. Research Papers, no. 2 (December 21, 2017): 27–59. Accessed July 22, 2026. https://bjiep.e-dnrs.org/index.php/rp/article/view/5611.