1. Recommended definitions, terminology and format for statistical tables related to the perinatal period and use of a new certificate for cause of perinatal deaths;World Health Organization;Acta Obstet. Gynecol. Scand.,1977
2. Epidemiology of preterm birth;Berkowitz;Epidemiol. Rev.,1993
3. The importance of preterm birth;Hall,1997
4. Accuracy of cervical transvaginal sonography in predicting preterm birth: a systematic review;Honest;Ultrasound Obstet. Gynecol.,2003
5. Prediction and early detection of preterm labor;Iams;Obstet. Gynecol.,2003