Mazza V, Falcinelli C, Paganelli S, etal (June 2001). «Sonographic early Foetal gender assignment: a longitudinal study in pregnancies after in vitro fertilization». Ultrasound Obstet Gynecol17 (6): 513-6. PMID11422974. doi:10.1046/j.1469-0705.2001.00421.x.
Mazza V, Falcinelli C, Paganelli S, etal (June 2001). «Sonographic early Foetal gender assignment: a longitudinal study in pregnancies after in vitro fertilization». Ultrasound Obstet Gynecol17 (6): 513-6. PMID11422974. doi:10.1046/j.1469-0705.2001.00421.x.