DRĖGŪNAS, V. Solid geometry classes at an eight-year school. Psichologija, [S. l.], v. 6, p. 5–19, 1964. DOI: 10.15388/Psichol.1964.6.8896. Disponível em: https://www.zurnalai.vu.lt/psichologija/article/view/8896. Acesso em: 9 nov. 2025.