SANSONE, F. J. The Backward and Forward Summation of Infinite Series of Isols. MATHEMATICA SCANDINAVICA, [S. l.], v. 24, p. 217–220, 1969. DOI: 10.7146/math.scand.a-10932. Disponível em: https://www.mscand.dk/article/view/10932. Acesso em: 5 may. 2024.