1. Midwifery and childbirth in America;Rooks,1997
2. American College of Nurse-Midwives. Definition of midwifery practice. Available at: http://www.midwife.org/ACNM/files/ccLibraryFiles/Filename/000000001385/CNM%20CM%20CPM%20ComparisonChart%20082511.pdf. Accessed April 5, 2001.
3. Statement of policy: midwifery education and certification,2007
4. Trends and characteristics of home and out-of-hospital births in the United States 1990-2006;MacDorman;Natl Vital Stat Rep,2010
5. Care in normal birth: a practical guide;World Health Organization,1996