1. Martin JA, Hamilton BE, Osterman MJ. Three decades of twin births in the United States. NCHS data brief. 1980-2009;2012(80):1–8.
2. Hilder L, Zhichao Z, Parker M, Jahan S, Chambers G. Australia's mothers and babies 2012. Perinatal statistics series no. 30. Cat. no. PER 69. In: Perinatal statistics series no. 30. Cat. no. PER 69. Canberra: Australian Institute of Health and Welfare; 2014.
3. Lancaster P, Pedisich EL, Huang J. Australia's Mothers and Babies 1992. In: Perinatal Statistics Series no. 2. National Perinatal Statistics Unit. Canberra: Australian Institute of Health and Welfare; 1995.
4. Domingues AP, Dinis SR, Belo A, Couto D, Fonseca E, Moura P. Impact of induced pregnancies in the obstetrical outcome of twin pregnancies. Fertil Steril. 2014;101(1):172–7.
5. Sunderam S, Kissin DM, Crawford SB, Folger SG, Jamieson DJ, Barfield WD. Assisted reproductive technology surveillance—United States, 2011. MMWR Surveil Summ. 2014;63(SS-10):1–28.