Markova, K. T., Dovramadjiev, T. A. and Jecheva, G. V. (2018) “Methodology for creating 3D paper unfolded models with complex geometry using open-source software and resources with free personal and commercial license”, ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA, 2(1), pp. 39–46. doi: 10.29114/ajtuv.vol2.iss1.67.