1. Kolthoff I. M., Belcher R. (1957) Volumetric Analysis, Vol. 3. Interscience, New York
2. Wilson C. L., Wilson D. W. (eds) (1960) Comprehensive Analytical Chemistry, Vol. 1B. Elsevier, Amsterdam
3. British Standards 1121, Part 38 (1967)
4. Arnold J. P., Johnson R. M. (1969) Talanta16: 1191
5. Kolthoff I. M., Probst R. L. (1949) Anal. Chem.21: 753