A Prospective Randomized Study of Hydrophilic Polymer-Coated Polyurethane Versus Polyethylene Stents in Distal Malignant Biliary Obstruction - van Berkel, A M; Bruno, M J; Bergman, J J G H M; van Deventer, S J H; Tytgat, G N J; Huibregtse, K (Endoscopy, 2003)