KALENDA, Česlovas. Improving the Methods of Teaching. Problemos, [S. l.], v. 4, p. 109–110, 1969. DOI: 10.15388/Problemos.1969.4.5767. Disponível em: https://www.zurnalai.vu.lt/problemos/article/view/5767. Acesso em: 7 nov. 2025.