References
- N. L. Biggs, Discrete Mathematics, Oxford University Press, Oxford, 1985.
- R. A. Brualdi, Introductory Combinatorics, Elsevier North-Holland, New York, 1977.
- D. S. Clark and J. T. Lewis, Avoiding-sequences with minimum sum. Discrete Applied Math., 22 (1988/89) 103–108.
- D. I. A. Cohen, Basic Techniques of Combinatorial Theory, Wiley, New York, 1978.
- M. Gilpin and R. Shelton, Forced differences between terms of subsequences of integer sequences, Proc. AMS 88 (1983) 569–578.
- R. P. Grimaldi, Discrete and Combinatorial Mathematics, Addison-Wesley, Reading, MA, 1985, p. 82.
- C. L. Liu, Elements of Discrete Mathematics, McGraw-Hill, New York, 1977.
- F. S. Roberts, Applied Combinatorics, Prentice-Hall, Englewood Cliffs, 1984.
- A. Tucker, Applied Combinatorics, 2nd ed., Wiley, New York, 1984.