Predictors of gallstone composition in 1025 symptomatic gallstones from Northern Germany - Schafmayer, C; Hartleb, J; Tepel, J; Albers, S; Freitag, S; Voelzke, H; Buch, S; Seeger, M; Timm, B; Kremer, B; Foelsch, U R; Faendrich, F; Krawczak, M; Schreiber, S; Hampe, J (BMC Gastroenterol, 2006)