1. J. Mitchell and D. M. Smith, Aquametiy, Part 3. John Wiley & Son, New York 1980.
2. C. Harris, Talanta, 19 (1972) 1523.
3. J. Mitchell and D. M. Smith, Aquametry, Part 1. John Wiley & Son, New York 1977.
4. M. B. Jacobs, The chemical analysis of food and food products, Van Nostrand Comp., New York 1951.
5. K. Fischer, Angew Chem., 48 (1935) 394.