TSCHAZKAJA, J. Über gewisse Masse. Lithuanian Mathematical Journal, [S. l.], v. 5, n. 3, p. 517–524, 1965. DOI: 10.15388/LMJ.1965.19607. Disponível em: https://www.journals.vu.lt/LMJ/article/view/19607.. Acesso em: 8 may. 2024.