Shaeer KZM, Osegbe DN, Siddiqui SH, Razzaque A, Glasser DB, Jaguste V. Prevalence of erectile dysfunction and its correlates among men attending primary care clinics in three countries: Pakistan, Egypt, and Nigeria. International Journal of Impotence Research. 2003 Apr 01;15(Suppl 1):s8–s14. doi: 10.1038/sj.ijir.3900971.