LEHOFER, Anna. Decrypting Historical Ciphers - A Way of Mathematical Competence Development. Opus et Educatio, [S. l.], v. 7, n. 2, 2020. 10.3311/ope.381. Disponível em: https://journals.bme.hu/oee/article/view/39180. Acesso em: 13 márc. 2025.