1. Philosophy of the American College of Nurse-Midwives,2004
2. Clinical Management Guidelines for Obstetrician‐Gynecologists, Number 62;Obstetrics and Gynecology,2005
3. Systems to rate the strength of scientific evidence. Fact sheet,2002
4. The limit of viability–neonatal outcome of infants born at 22 to 25 weeks’ gestation;Allen;New England Journal of Medicine,1993
5. Early skin‐to‐skin contact for mothers and their healthy newborn infants;Anderson,2003