Adjuvant chemotherapy with gemcitabine vs observation in patients undergoing curative-intent resection of pancreatic cancer: a randomized controlled trial. - Oettle H; Post S; Neuhaus P; Gellert K; Langrehr J; Ridwelski K; Schramm H; Fahlke J; Zuelke C; Burkart C; Gutberlet K; Kettner E; et al. (JAMA: Journal of the American Medical Association, 2007)