MAZHUGA, Yu. I. Operator methods in the problem of estimating the asymptotics of the time of the first hit for the birth and death process. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 8, p. 1104–1108, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5906. Acesso em: 5 dec. 2025.