Evaluation of Varicose Veins of the Lower Extremity: the Value of the Duplex Ultrasound (Part 1) - Spinedi, L.; Broz, P.; Baldi, T.; Imfeld, S.; Staub, D.; Jaeger, K.; Aschwanden, M.; Uthoff, H. (Ultraschall in der Medizin - European Journal of Ultrasound, 2016)