Tawfik WM. Evaluation of yolk sac size and embryonic heart rate in first trimester and pregnancy outcome. Int J Reprod Contracept Obstet Gynecol [Internet]. 2021 Jul. 26 [cited 2025 Apr. 18];10(8):2975-80. Available from: https://www.ijrcog.org/index.php/ijrcog/article/view/10484