1. 1. Normal Labor, Chapter 22, Williams Obstetrics, 25th edition.
2. 2. Management of second stage of labor. In: Chandraharan E (Ed). The Continuous Textbook of Women's Medicine Series, Labor and Delivery Obstetrics Module, Vol. 11.
3. 3. Cohen W, Friedman EA. Clinical evaluation of labor: An evidence and experience based approach. J Perinat Med 2020. DOI: 10.1515/jpm-2020-0256.
4. 4. Abnormal labor, Chapter 23. In Cunningham F, Leveno KJ, Bloom SL, (Eds.), Williams Obstetrics, McGraw Hill: 2018:25e.
5. 5. Abnormal Labor Patterns, Prolonged Labor, Chapter 21. In: Sharma JB (Ed). Textbook of Obstetrics, 2nd edition.