1. Development of methods of male contraception: impact of the World Health Organization Task Force 
Geoffrey M.H. Waites, Sc.D. 
Fertility and Sterility 
Volume 80, Issue 1, Pages 1-15 (July 2003)
DOI: /S (03)

2. FIGURE 1
The structure of the World Health Organization collaborative research program on Tripterygium wilfordii (30).
Waites. WHO and male contraception. Fertil Steril 2003.
Fertility and Sterility  , 1-15DOI: ( /S (03) )

3. FIGURE 2
Relationship between sperm concentration and pregnancy rate in the World Health Organization contraceptive efficacy trial (39). Pregnancy rates per 100 person-years in each sperm concentration stratum (inset), and according to the cumulative sperm concentration. Bars indicate 95% confidence limits, and numbers in brackets are the number of pregnancies observed.
Waites. WHO and male contraception. Fertil Steril 2003.
Fertility and Sterility  , 1-15DOI: ( /S (03) )