& AKINREFON A.A., A. O. First Birth Interval: Cox Regression Model with Time Varying Covariates. Covenant Journal of Physical and Life Sciences, [S. l.], 2018. Disponível em: https://journals.covenantuniversity.edu.ng/index.php/cjpls/article/view/930. Acesso em: 28 apr. 2024.