Neykov, Nikolay, Radostina Popova-Terziyska, and Emil Kitchoukov. “DATA ENVELOPMENT ANALYSIS OF FACTORS FOR FOREST INDUSTRY WAGES AND SALARIES LEVELS IN NUTS 2 REGIONS OF BULGARIA”. Innovation in Woodworking Industry and Engineering design 12, no. 1 (May 30, 2023). Accessed April 14, 2026. http://innojs.ltu.bg/index.php/scjournal-inno/article/view/350.