1. The Methuen Handbook of Colour;Kornerup,1967
2. The application of a standard colour coding system to paint in forensic science;Fouweather;J. Forensic Sci.,1976
3. J. Porter, (1976) unpublished results.
4. Official recommendation of the International Commission on Illumination;CIE;CIE Publication No. 15,1971
5. Colour tolerance specification;Nickerson;J. Opt. Soc. Am.,1944