Tsonkov, Nikolay, Kamen Petrov, and Tzvetelina Berberova–Valcheva. “Intelligent Development and Connectedness in the Context of the Regional Development”. UNWE Yearbook, no. 2 (February 6, 2023): 117–131. Accessed July 22, 2026. https://bjiep.e-dnrs.org/index.php/yb/article/view/5883.