1. Lowdermilk Leonard Deitra, Perry Shannon E. Maternity and womens health care. 9th ed. China: Mosby Elsevier; 2007. P.313, 316, 335, 345-6.
2. Wong Donna L, Perry Shannon E. Maternal and child nursing care. 1st ed. United States of America: Mosby; 1998. P.58, 79
3. Fraser Diane M, Cooper Margaret A. Myles textbook for midwives. 14th ed. Edinburgh: Churchill Livingstone; 2003. P. 123, 129, 198-201, 331-2.
4. Lewis Sharon L, Heitkemper Margaret Melean, Dirksen Shannon Ruff, O’ Brien Patricia Graber, Bucher Linda, Mani Mrinaline, et al. Lewis’s medical-surgical nursing assessment and management of clinical problems. 1st ed. Delhi: Reed Elsevier India (Pvt) Ltd; 2011. P.1161-73.
5. Smeltzer Suzanne C, Bare Brenda G. Brunner and suddarth’s textbook of medical-surgical nursing. 10th ed. Philadelphia: Lippincott Williams and Wilkins; 2004. P.1310.