1. Japanese Industrial Standard: JIS Z 8513 (1994).
2. International Standard: ISO 9241–3 (1992).
3. A. Cakir, D. J. Hart, and T. F. Stewart: Workplace Design, Health and Safety, Task Organization (John Wiley & Sons, New York, 1980).
4. Deutsches Institut fur Normung: DIN 66234, Teil 1 (1980).
5. G. E. Legge, D. G. Pelli, G. S. Rubin, and M. M. Schleske: Vision Res. 25 (1985) 239.