3) Isayama H, Komatsu Y, Tsujino T, et al. A prospec-tive randomised study of "covered" versus "uncov-ered" diamond stents for the management of distal malignant biliary obstruction. Gut 53 729-734, 2004.
4) Isayama H, Komatsu Y, Tsujino T, et al. Polyure-thane-covered metal stent for management of distal malignant biliary obstruction. Gastrointest Endosc 55 366-370, 2002.
5) Nakai Y, Isayama H, Komatsu Y, et al. Efficacy and safety of the covered Wallstent in patients with dis-tal malignant biliary obstruction. Gastrointest Endosc 62 742-748, 2005.