Jens Langhoff-Roos, Ulrik Kesmodel, Bo Jacobsson, Steen Rasmussen, Ida Vogel
Langhoff-Roos J, Kesmodel U, Jacobsson B, Rasmussen S, Vogel I.
Spontaneous preterm delivery in primiparous women at low risk in Denmark: population based study
BMJ 2006; 332 :937
doi:10.1136/bmj.38751.524132.2F