ABBOTT, M.; COHEN, B. Vertical integration, separation in the rail industry: a survey of empirical studies on efficiency. European Journal of Transport and Infrastructure Research, [S. l.], v. 17, n. 2, 2017. DOI: 10.18757/ejtir.2017.17.2.3191. Disponível em: https://journals.open.tudelft.nl/ejtir/article/view/3191. Acesso em: 3 dec. 2021.