Cole JA, Rothman KJ, Cabral HJ, Zhang Y, Farraye FA. Incidence of IBS in a cohort of people with asthma. Dig Dis Sci. 2007 Feb 28;52(2):329-35.
Norton EC, Zarkin GA, Calingaert B, Bradley CJ. The effect of maternal substance abuse on the cost of neonatal care. Inquiry. 1996;33(3):247-57.