Lash TL, Johansen MB, Christensen S, Baron JA, Rothman KJ, Hansen JG, Sorensen HT. Hospitalization rates and survival associated with COPD: a nationwide Danish cohort study. Lung. 2011 Feb 1;189(1):27-35.
Nguyen USDT, Rothman KJ, Demissie S, Jackson DJ, Lang JM, Ecker JL. Transfers among women intending a birth center delivery in the San Diego birth center study. J Midwifery Womens Health. 2009 Mar 1;54(2):104-10.