Cueto HT, Riis AH, Hatch EE, Wise LA, Rothman KJ, Sørensen HT, Mikkelsen EM. Folic acid supplementation and fecundability: a Danish prospective cohort study. Eur J Clin Nutr. 2016 Jan;70(1):66-71. doi: 10.1038/ejcn.2015.94
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.