1. Standardizing diagnostic procedures;Kahn;Am J Ophthalmol,1975
2. Variability of expert observers in evaluating the optic disc;Lichter;Trans Am Ophthalmol Soc,1976
3. Measurement vs. judgement of cup-disc ratios: statistical evaluation of intraobserver and interobserver error;Cooper;Glaucoma,1982
4. Interobserver variations in tonometry and optic disc assessment;Biedner;Glaucoma,1983
5. Quantitation of optic disc cupping;Klein;Ophthalmology,1985