1. H. Weing�rtner, B. M. Braun, and J. M. Schmoll,J. Phys. Chem. 91, 979 (1987); references cited therein.
2. R. A. Robinson and R. H. Stokes,Electrolyte Solutions, 2nd edn., (Butterworths, London, 1970).
3. M. Spiro, inPhysical Methods of Chemistry, B. W. Rossiter, ed., (Wiley, New York, 1986).
4. A. K. Covington, inIon-Selective Electrode Methodology A. K. Covington, ed., (CRC Press, Boca Raton, Fl., 1979), Chap. 1.
5. J. N. Butler inActivity Coefficients in Electrolyte Solutions, R. M. Pytkowicz ed., (CRC Press, Boca Raton, FL., 1979), Vol. 1, Chap. 4.