Derek A. Holton Brendan D. McKay The smallest non-hamiltonian 3-connected cubic planar graphs have 38 vertices. 305-319 1988 45 J. Comb. Theory, Ser. B 3 http://dx.doi.org/10.1016/0095-8956(88)90075-5 db/journals/jct/jctb45.html#HoltonM88