1. Koblinsky M, Campbell O, Heichelheim J. Organizing delivery care: what works for safe motherhood?Bull World Health Organ. 1999;77:399–406
2. Graham W, Bell J, Bullough C. Can skilled attendance at delivery reduce maternal mortality in developing countries? In: Studies in Health Services, Organisation, and Policy. Antwerp, Belgium: Prince Leopold Institute of Tropical Medicine; 2001:97–129
3. Sibley L, Sipe T. Traditional Birth Attendant Training Effectiveness: A Meta-analysis. Final Technical Report. Washington, DC: Academy for Educational Development/Sara Project; 2002
4. Bale J, Stoll B, Lucas A, eds. Improving Birth Outcomes: Meeting the Challenge in the Developing World. Committee on Improving Birth Outcomes, Board on Global Health. Washington, DC: The National Academies Press; 2003
5. Concato J, Horwitz R. Beyond randomised versus observational studies. Lancet. 2004;363:1660–1661