Constipation - Nasseri, Yosef; Duthie, Graeme S.; Bartolo, D.C.C; Duthie, Graeme; Duthie, Graeme S.; Wexner, Steven D.; Bartolo, D. C. C. (Bethesda, Md. U.S. Department of Health and Human Services, National Institutes of Health, National Cancer Insititute, 2012)