Kotz Daniel, Spigt Mark, Arts Ilja C W, Crutzen Rik, Viechtbauer Wolfgang
Department of General Practice, CAPHRI School for Public Health and Primary Care, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
J Clin Epidemiol. 2012 Dec;65(12):1249-52. doi: 10.1016/j.jclinepi.2012.06.004. Epub 2012 Sep 8.