OKAFOR, F. C. The theory and application of sampling over two occasions for the estimation of current population ratio. Statistica, [S. l.], v. 52, n. 1, p. 137–147, 1992. DOI: 10.6092/issn.1973-2201/897. Disponível em: https://rivista-statistica.unibo.it/article/view/897. Acesso em: 2 dec. 2021.