1. WHO. Public health surveillance. Geneva: WHO; 2018.
http://www.who.int/topics/public_health_surveillance/en/
. Accessed 30 May 2018.
2. WHO. Report on the meeting on post-endemic surveillance for blinding trachoma. Geneva: WHO; 2008.
3. WHO. Resolution WHA51.11. Global elimination of blindign trachoma In: 51st World Health Assembly. Geneva, 16 May 1998. Geneva: WHO; 1998.
4. Thylefors B, Dawson CR, Jones BR, West SK, Taylor HR. A simple system for the assessment of trachoma and its complications. Bull World Health Org. 1987;65(4):477–83.
5. WHO. Trachoma control: a guide for Programme managers. Geneva: WHO; 2006.