Grancharova-Hristova M, Moraliyska N, Glushkova T, Rusev K. Virtualization, Processing, and Standardization of Knowledge about Bulgarian Cultural, Historical and Natural Heritage for Use in School Education. DiPP [Internet]. 2022 Sep. 7 [cited 2024 Apr. 24];12:131-40. Available from: https://dipp.math.bas.bg/dipp/article/view/dipp.2022.12.10