Comparison of 1% and 3% polidocanol foam in ultrasound guided sclerotherapy of the great saphenousvein: a randomised, double-blind trial with 2year-follow-up. „The 3/1 Study“ - Hamel-Desnos, C; Ouvry, P; Benigni, JP; Boitelle, G; Schadeck, M; Desnos, P; Allaert, FA (Eur J Vasc Endovasc Surg, 2007)