ALTSCHUL, R. Another Proof for a Combinatorial Lemma in Fluctuation Theory. Mathematica Scandinavica, Berkeley, CA, United States, v. 31, p. 123–126, 1972. DOI: 10.7146/math.scand.a-11419. Disponível em: https://journals.msp.org/mscand/article/view/2223. Acesso em: 25 jul. 2026.