Bateni ZH, Clark SL, Sangi-Haghpeykar H, Aagaard KM, Blumenfeld YJ, Ramin SM, Lee HC, Fox KA, Moaddab A, Shamshirsaz AA, Salmanian B, Hosseinzadeh P, Racusin DA, Erfani H, Espinoza J, Dildy GA, Belfort MA, Shamshirsaz AA. Trends in the delivery route of twin pregnancies in the United States, 2006-2013. Eur J Obstet Gynecol Reprod Biol. 2016 Oct; 205:120-6.