1. Crossing Number is NP-Complete
2. R. K. Guy, The decline and fall of Zarankiewicz's theorem in Proof Techniques in Graph Theory, Academic Press, New York, 1969, pp. 63–69.
3. F. Harary, Graph Theory, Addison Wesley, Reading, MA, 1972.
4. The crossing number of K5,n
5. A note of welcome