Outcomes and side effects of duplex-guided sclerotherapy in the treatment of great saphenous veins with 1% versus 3% Polidocanol foam: Results of a randomized controlled trial with 1-year follow-up - Ceulen, RPM; Bullens-Goessens, YIJM; Pi-Van De Venne, SJA (Dermatol Surg, 2007)