Fetal volume and crown-rump length from 7 to 10 weeks of gestational age in singletons and twins - Martins, Wellington de Paula; Nastri, Carolina Oliveira; Barra, Daniela de Abreu; Navarro, Paula Andrea de Albuquerque Salles; Mauad Filho, Francisco; Ferriani, Rui Alberto (European Journal of Obstetrics & Gynecology and Reproductive Biology, 2009)