Noev, Nikolay, Iliya Valev, Stefka Kancheva, and Vladimir Sapundjiev. 2018. “A Model of Content Structure for a Serious Educational Game Related to the Military and Historical Heritage Presented through the ‘Mission Opalchenets’”. Digital Presentation and Preservation of Cultural and Scientific Heritage 8 (September):151-58. https://doi.org/10.55630/dipp.2018.8.13.