1. Bron, AJ, Brown, NAP. Classification, grading and prevention of cataract. IBID 1983; 4: 21?47.
2. Chylack LT, Bettelheim FA, Tung WH. Studies on human cataracts, 1. Evaluation of techniques of human cataract preservation after extraction. Invest Ophthalmol Vis Sci 1981; 20: 327?333.
3. Chylack LT, Lee MR, Tung WH, Cheng HM. Classification of human senile cataractous change by the American Cooperative Cataract Research Group (CCRG) method, 1. Instrumentation and technique. Invest Ophthalmol Vis Sci 1983; 24: 424?431.
4. Chylack LT, Ransil BJ, White O. Classification of human senile cataractous change by the American co-operative cataract research group method, 3. The association of nuclear colour (sclerosis) with extent of cataract formation, age and visual acuity. Invest Ophthalmol 1984; 25: 174?180.
5. Clayton RM, Cuthbert J, Phillips CI, Bartholomew RS, Stokoe NL, Ffytche T, McKeid J, Duffy J, Seth J, Alexander M. Analysis of individual cataract patients and their lenses: A progress report. Exp Eye Res 1980; 31: 553?566.