ZENKL, David. Presentation of combinatorial concepts in mathematics textbooks and its compliance with a concept development theory. Scientia in educatione, [S. l.], v. 12, n. 1, p. 37–52, 2021. DOI: 10.14712/18047106.1938. Disponível em: https://test.scied.cz/scied/article/view/1938. Acesso em: 21 may. 2026.