JATKONIS, G. Why We Change Concepts. Problemos, [S. l.], v. 27, p. 80–81, 1982. DOI: 10.15388/Problemos.1982.27.6313. Disponível em: https://www.journals.vu.lt/problemos/article/view/6313.. Acesso em: 7 may. 2024.