Ugá, M. A. D., Vasconcellos, M. M., Lima, S. M. L., Portela, M. C., & Gerschman, S. (2009). Mechanisms of microregulation of private hospitals by health plan operators . Revista De Saúde Pública, 43(5), 832-838. https://doi.org/10.1590/S0034-89102009005000053