1. S. Akl, A lower bound on the maximum number of crossing-free Hamilton cycles in a rectilinear drawing ofK n ,Ars Combin. 7 (1979), 7–18.
2. M. Ajtai, V. Chvátal, M. Newborn, and E. Szemerédi, Crossing-free subgraphs,Ann. Discrete Math. 12 (1982), 9–12.
3. P. Erdos and R. K. Guy, Crossing number problems,Amer. Math. Monthly 80 (1973), 52–58.
4. R. K. Guy, Unsolved problems,Amer. Math. Monthly 88 (1981), 757.
5. R. B. Hayward, The Optimal Crossing-Free Hamilton Cycle Problem for Planar Drawings of the Complete Graph, M.Sc. thesis, Queen's University, Kingston, Ontario, 1982.