Ivanova, Krassimira, Iliya Mitov, and Peter Stanchev. “Establishing Correspondences Between Attribute Spaces and Complex Concept Spaces Using Meta-PGN Classifier”. Digital Presentation and Preservation of Cultural and Scientific Heritage 2 (September 30, 2012): 71–77. Accessed May 6, 2024. https://dipp.math.bas.bg/dipp/article/view/dipp.2012.2.28.