1. University Medical Centre Mannheim, University of Heidelberg; Department of Surgery; Theodor-Kutzer-Ufer 1-3 Mannheim Baden-Württemberg Germany 68167
2. Institute of Medical Biometry and Medical Informatics, University Medical Center Freiburg; German Cochrane Centre; Berliner Allee 29 Freiburg Germany 79110
3. University Medical Centre Mannheim, University of Heidelberg; Library; Theodor-Kutzer-Ufer 1-3 Mannheim Baden-Wurttemberg Germany 68167