1. J. Buhler, D. Eisenbud, R. Graham, and C. Wright, Juggling drops and descents, Amer. Math. Monthly, to appear.
2. F. R. K. Chung and R L. Graham, Digraph polynomials, submitted for publication.
3. Concrete Mathematics: A Foundation for Computer Science;Graham,1989
4. Chromatic polynomials;Read,1988