1. A critical evaluation of sonar “crown rump length” measurements;Robinson;Br J Obstet Gynaecol,1975
2. Comparison of methods for determining crown rump measurement by realtime ultrasound;Nelson;JCU,1981
3. Estimation of gestational age during the first trimester of realtime measurement of fetal crown rump length and biparietal diameter;Bovicelli;JCU,1981
4. Embryonic trunk circumference: a new biometric parameter for estimation of gestational age;Reece;Am J Obstet Gynecol,1987
5. Pilu G, Hobbins JC. The normal and abnormal developmental anatomy of the fetal central nervous system as derived from realtime high resolution ultrasound. Clin Diagn Ultrasound (in press)