TY - JOUR AU - Ekbom, A; Helmick, C; Zack, M TI - Ulcerative colitis and colorectal cancer. A population-based study JO - N Engl J Med VL - 323 PY - 1990 DO - 10.1056/NEJM199011013231802 L3 - PubMed-ID: 2215606 SP - 1228 EP - 1233 N1 - et al. ER -