ANDERSEN, E. S. Two summation formulae for product sums of binomial coefficients. MATHEMATICA SCANDINAVICA, [S. l.], v. 1, p. 261–262, 1953. DOI: 10.7146/math.scand.a-10384. Disponível em: https://www.mscand.dk/article/view/10384. Acesso em: 6 may. 2024.