Jeddi, S. Z., N. Mobaraki, and A. Pirzadeh. “Transvaginal Ultrasound Compared With Serum β-HCG Level for Diagnosis of Ectopic Pregnancy in Symptomatic Patients”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, vol. 9, no. 3, Feb. 2020, pp. 1228-33, doi:10.18203/2320-1770.ijrcog20200905.