Iams JD, Romero R, Culhane JF, Goldenberg RL (2008). "Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth". The Lancet. 371 (9607): 164–175. doi:10.1016/S0140-6736(08)60108-7. PMID18191687.
Iams JD, Romero R, Culhane JF, Goldenberg RL (2008). "Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth". The Lancet. 371 (9607): 164–175. doi:10.1016/S0140-6736(08)60108-7. PMID18191687.