Chowdhury, Rajib Nayan, et al. “Digital Subtraction Angiogram (DSA) Is Superior to Duplex Ultrasound (USD) in Diagnosis of Extracranial Carotid Stenosis - A Comparative Study”. Journal of Medicine, vol. 12, no. 1, Jan. 2011, pp. 12-16, doi:10.3329/jom.v12i1.6926.