References
1. Dudek R W, 2001, High-yield embryology, 3rd edition. Baltimore, USA: Lippincott Williams & Wilkins.
2. Moore K L, Persaud T V N and Torchia M G, 2008, Before we are born essentials of embryology and birth defects, 8th edition. Philadelphia, USA: Elsevier.
3. Sadler T W, 2006, Langman's medical embryology, 10th edition. Baltimore, USA: Lippincott Williams & Wilkins.
4. Siddiqui I A and Usmani S, 2001, Sharjeel's human embryology, 3rd edition. Karachi,Pakistan: Dow Thought Provokers & Medincite.
2. Moore K L, Persaud T V N and Torchia M G, 2008, Before we are born essentials of embryology and birth defects, 8th edition. Philadelphia, USA: Elsevier.
3. Sadler T W, 2006, Langman's medical embryology, 10th edition. Baltimore, USA: Lippincott Williams & Wilkins.
4. Siddiqui I A and Usmani S, 2001, Sharjeel's human embryology, 3rd edition. Karachi,Pakistan: Dow Thought Provokers & Medincite.