1. 1. Woddell K. Spherical refraction for general eye workers. Commun Eye Health 2000;13(33):6-7.
2. 2. Dondona R, Dondona L. Refractive error blindness. Bull World Health Organ 2001;79(3):237-43.
3. 3. Danish Assistance to the National Programme for Control of Blindness. New Delhi, India: Vision screening in school children. Training module 1.
4. 4. Gilbert C, Foster A. Childhood blindness in the context of VISION 2020-the right to sight. Bull World Health Organ 2001;79(3):227-32.
5. 5. Negrel AD, Ellwein LB. More research needed to assess the magnitude of refractive errors world-wide. Commun Eye Health 2000;13(33):11-2.