Mangel AW, Fehnel SE. End points in irritable bowel syndrome. Expert Rev Gastroenterol Hepatol. 2011 Jun 1;5(3):293-5.
Williams RE, Bosnic N, Sweeney CT, Duncan AW, Levine KB, Brogan M, Cook SF. Prevalence of opioid dispensings and concurrent gastrointestinal medications in Quebec. Pain Res Manag. 2008;13(5):395-400.
Rothman KJ. Computation of exact confidence intervals for the odds ratio. Int J Biomed Comput. 1975 Jan;6(1):33-9.
Rothman KJ. Computer analysis for case-control studies with individual matching. Int J Biomed Comput. 1974 Oct;5(4):241-7.