1. Periodic health examination, 1992 update: 2. Routine prenatal ultrasound screening. Canadian Task Force on the Periodic Health Examination. Can Med J 1992;147(5):627-633.
2. Guidelines for the performance of ultrasound examination in obstetrics and gynaecology;J Soc Obstet Gynaecol Can,1995
3. Obstetric/gynaecologic ultrasound [policy statement];J Soc Obstet Gynaecol Can,1997
4. Ultrasound screening and perinatal mortality: controlled trial on systematic one-stage screening in pregnancy. The Helsinki Ultrasound Trial;Saari-Kemppainen;Lancet,1990
5. Cost-effectiveness of one-stage ultrasound screening in pregnancy: a report from the Helsinki ultrasound trial;Leivo;Ultrasound Obstet Gynecol,1996