Markova, Kremena, Tihomir Dovramadjiev, and Ginka Jecheva. ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA 1, no. 1 (December 28, 2017): 77-84. Accessed August 20, 2025. http://194.141.24.9/index.php/ajtuv/article/view/44.