Peters David H, Adam Taghreed, Alonge Olakunle, Agyepong Irene Akua, Tran Nhan
Johns Hopkins University Bloomberg School of Public Health, Department of International Health, 615 N Wolfe St, Baltimore, MD 21205, USA.
BMJ. 2013 Nov 20;347:f6753. doi: 10.1136/bmj.f6753.