Simone Dantas Sylvain Gravier Frédéric Maffray Extremal graphs for the list-coloring version of a theorem of Nordhaus and Gaddum. 93-101 2004 141 Discrete Applied Mathematics 1-3 http://dx.doi.org/10.1016/S0166-218X(03)00377-9 db/journals/dam/dam141.html#DantasGM04