Graça, L. M., Clode, N., Cardoso, C. G., Colaço, A., Casal, E., Jorge, A. F., Ferreira, H., Pereira, R., Martins, C., & Silva, M. O. (1991). Doppler flowmetry of feto-maternal circulation: III --Absent and reverse diastolic flow in the umbilical artery. Acta Médica Portuguesa, 4(3), 127–30. https://doi.org/10.20344/amp.3345