↑ Lehninger, A.L., Nelson, D.L., and Cox, M.M. 1993. Principle of Biochemistry. 2nd ed. New York.: Worth
Doolittle, R.F. (1989) Redundancies in protein sequences. In Predictions of Protein Structure and the Principles of Protein Conformation (Fasman, G.D. ed) Plenum Press, New York, pp. 599-623
David L. Nelson and Michael M. Cox, Lehninger Principles of Biochemistry, 3rd edition, 2000, Worth Publishers, ISBN 1-57259-153-6
