@article{DCG_1987__2_131026,
     author = {R.B. Hayward},
     title = {A {Lower} {Bound} for the {Optimal} {Crossing-Free} {Hamiltonian} {Cycle} {Problem.}},
     journal = {Discrete & computational geometry},
     pages = {327--344},
     publisher = {mathdoc},
     volume = {2},
     year = {1987},
     zbl = {0623.05037},
     url = {http://geodesic.mathdoc.fr/item/DCG_1987__2_131026/}
}