American Journal of Obstetrics and Gynecology
American Journal of Obstetrics and Gynecology > 1995 > 172 > 3 > 955-959
American Journal of Obstetrics and Gynecology > 2006 > 195 > 4 > 899-906
American Journal of Obstetrics and Gynecology > 2012 > 207 > 5 > 410.e1-410.e6