References
- Becker H, Nelson MM. 1987. The extra-embryonic coelom on ultrasonography. South African Medical Journal Suid-Afrikaanse Tydskrif Vir Geneeskunde 71:334.
- Howe RS. 1996. Early pregnancy: normal and abnormal. Clinical Obstetrics and Gynecology 39:188–198.
- Kurjak A, Kupesic S, Ahmad B. 2008. Ultrasound evaluation of abnormal early pregnancy. In: Kurjak A, Chervenak FA, editors. Donald school textbook of ultrasound in obstetrics and gynecology. 2nd ed. New Delhi: Jaypee Brothers Medical Publishers. p. 209–230.
- Lindsay DJ, Lovett IS, Lyons EA, Levi CS, Zheng XH, Holt SC, et al. 1992. Yolk sac diameter and shape at endovaginal US: predictors of pregnancy outcome in the first trimester. Radiology 183:115–118.
- Moore KL, Persaud TVN. 2011. Second week of human development. The developing human: clinically oriented embryology. 9th ed. Philadelphia: Saunders. p. 41–52.
- Perni SC, Andonotopo W, Stanojevic M. 2008. Ultrasound evaluation of the multifetal gestation. In: Kurjak A, Chervenak FA, editors. Donald school textbook of ultrasound in obstetrics and gynecology. 2nd ed. New Delhi: Jaypee Brothers Medical Publishers. p. 473–487.
- Russo R, D’armiento M, Angrisani P, Vecchione R. 1993. Limb body wall complex: a critical review and a nosological proposal. American Journal of Medical Genetics 47:893–900.
- Sadler TW. 2011. Second week of development: bilaminar germ disc. Langman’s medical embryology. 12th ed. Philadelphia: Lippincott Williams and Wilkins. p. 43–50.