Stanchev, Peter, Guenoveva Jecheva, and Radoslav Pavlov. “The Sixth National Information Day: Open Access to Scientific Information”. Digital Presentation and Preservation of Cultural and Scientific Heritage 5 (September 30, 2015): 365–369. Accessed May 5, 2024. https://dipp.math.bas.bg/dipp/article/view/dipp.2015.5.35.