1. D. O. Gol'dberg, Control of Oil and Paraffin Wax Production [in Russian], Khimiya, Moscow (1964).
2. M. M. Gurevich, Color and Its Measurement [in Russian], Izd. Akad. Nauk SSSR, Moscow (1950).
3. B. M. Rybak, Analysis of Crude Oils and Products [in Russian], Gostoptekhizdat, Moscow (1962).
4. D. B. Judd and G. Wyszecki, Color in Business, Science, and Industry, 2nd edn., Wiley, New York (1963).