1. Greenstein, J.P., Winitz, M.: Chemistry of the Amino Acids. Wiley, New York (1961)
2. Edsall, J.T., Blanchard, M.H.: The activity ratio of zwitterions and uncharged molecules in ampholyte solutions. The dissociation constants of amino acid esters. J. Am. Chem. Soc. 55, 2353–2337 (1933)
3. Harris, L.J.: Note on the dissociation constants of certain amino acids, including valine, glutamic acid. J. Biol. Chem. 84, 179–181 (1929)
4. Miyamoto, S., Schmidt, C.L.A.: The apparent dissociation constants of phenylalanine and of dihydroxyphenylalanine and the apparent free energy and entropy changes of certain amino acids due to ionization. J. Biol. Chem. 90, 165–178 (1931)
5. Kortüm, G., Vogel, W., Andrussow, K.: Dissociation Constants of Organic Acids in Aqueous Solution. Butterworths, London (1961)