GANELIUS, T.; FREUD, G. Some remarks on one-sided approximation. MATHEMATICA SCANDINAVICA, [S. l.], v. 5, p. 276–284, 1957. DOI: 10.7146/math.scand.a-10506. Disponível em: https://www.mscand.dk/article/view/10506. Acesso em: 2 may. 2024.