Rauf, Muhammad Haris, et al. “Frequency of Sapheno-Femoral Junction and Sapheno-Popliteal Junction Incompetence on Duplex Ultrasonography in Patients With Varicose Veins”. Pakistan Armed Forces Medical Journal, vol. 72, no. 1, Feb. 2022, pp. 3-7, https://doi.org/10.51253/pafmj.v72i1.4071.