APA (7th ed.) Citation

Spencer, K., Souter, V., Tul, N., Snijders, R., & Nicolaides, K. H. (1999). A screening program for trisomy 21 at 10–14 weeks using fetal nuchal translucency, maternal serum free ß-human chorionic gonadotropin and pregnancy-associated plasma protein-A. Ultrasound in Obstetrics & Gynecology, 13(4), 231. https://doi.org/10.1046/j.1469-0705.1999.13040231.x

Chicago Style (17th ed.) Citation

Spencer, K., V. Souter, N. Tul, R. Snijders, and K. H. Nicolaides. "A Screening Program for Trisomy 21 at 10–14 Weeks Using Fetal Nuchal Translucency, Maternal Serum Free ß-human Chorionic Gonadotropin and Pregnancy-associated Plasma Protein-A." Ultrasound in Obstetrics & Gynecology 13, no. 4 (1999): 231. https://doi.org/10.1046/j.1469-0705.1999.13040231.x.

MLA (9th ed.) Citation

Spencer, K., et al. "A Screening Program for Trisomy 21 at 10–14 Weeks Using Fetal Nuchal Translucency, Maternal Serum Free ß-human Chorionic Gonadotropin and Pregnancy-associated Plasma Protein-A." Ultrasound in Obstetrics & Gynecology, vol. 13, no. 4, 1999, p. 231, https://doi.org/10.1046/j.1469-0705.1999.13040231.x.