Ferdous, MA, MM Sharif, AS Mohiuddin, and F Shegufta. 2013. “Normal Value of Pulsatility Index of Umbilical Artery in Second and Third Trimester of Pregnancy”. Bangladesh Medical Research Council Bulletin 39 (1):42-44. https://doi.org/10.3329/bmrcb.v39i1.15809.