ALTSCHUL, R. Another Proof for a Combinatorial Lemma in Fluctuation Theory. MATHEMATICA SCANDINAVICA, [S. l.], v. 31, p. 123–126, 1972. DOI: 10.7146/math.scand.a-11419. Disponível em: https://tidsskrift.dk/math/article/view/11419. Acesso em: 14 aug. 2026.