Costa-Martins, J.M., Dias, C.C., Pereira, M. and Tavares, J. 2015. Effects of Local Anesthetic on the Time Between Analgesic Boluses and the Duration of Labor in Patient-Controlled Epidural Analgesia: Prospective Study of Two Ultra-Low Dose Regimens of Ropivacaine and Sufentanil. Acta Médica Portuguesa. 28, 1 (Feb. 2015), 70–76. DOI:https://doi.org/10.20344/amp.5708.