Mathieu Liedloff Ton Kloks Jiping Liu Sheng-Lung Peng Efficient algorithms for Roman domination on some classes of graphs. 3400-3415 2008 156 Discrete Applied Mathematics 18 http://dx.doi.org/10.1016/j.dam.2008.01.011 db/journals/dam/dam156.html#LiedloffKLP08