References
- Arey L. B. Developmental Anatomy, seventh edition. Saunders, Philadelphia and London 1965; 109, 130–131
- Hamilton W. J., Mossman H. W. Textbook of Human Embryology, fourth edition. Williams & Wilkins, Baltimore 1972; 122
- Jouppila P., Huntaniemi I., Tapanainen J. Early pregnancy failure: Study by ultrasonic and hormonal methods. Obstet Gynecol 1979; 55: 42
- Langman J. Medical Embryology. Williams & Wilkins, Baltimore 1963; 63–69
- Mantoni M., Pedersen J. F. Ultrasound visualization of the human yolk sac. J Clin Ultrasound 1979; 7: 459
- Mantoni M., Pedersen J. F. Monoamniotic twins diagnosed by ultrasound in first trimester. Acta Obstet Gynecol Scand 1980; 59: 551
- Mantoni M., Pedersen J. F. Intrauterine haematome. An ultrasonic study of threatened abortion. Br J Obstet Gynaecol 1981; 88: 47
- Robinson H. P. The diagnosis of early pregnancy failure by sonar. Br J Obstet Gynaecol 1975; 82: 849
- Robinson H. P., Fleming J. E. E. A critical evaluation of sonar crown-rump length measurements. Br J Obstet Gynaecol 1975; 82: 702
- Saurbrei E., Cooperberg P. L., Poland B. J. Ultrasound demonstration of the normal fetal yolk sac. J Clin Ultrasound 1980; 8: 217