Noev, Nikolay, Maxim Goynov, Vladimir Sapundjiev, and Iliya Valev. “A Serious Educational Game of Bulgarian Military and Historical Heritage”. Digital Presentation and Preservation of Cultural and Scientific Heritage 7 (September 10, 2017): 249–254. Accessed March 29, 2024. https://dipp.math.bas.bg/dipp/article/view/dipp.2017.7.24.