Schulz Kenneth F, Grimes David A
FHI 360, PO Box 13950, Research Triangle Park, NC 27709, USA; Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7570, USA.
Contraception. 2013 Dec;88(6):676-7. doi: 10.1016/j.contraception.2013.10.002. Epub 2013 Oct 18.