David B. Chandler Maw-Shang Chang Ton Kloks Jiping Liu Sheng-Lung Peng On probe permutation graphs. 2611-2619 2009 157 Discrete Applied Mathematics 12 http://dx.doi.org/10.1016/j.dam.2008.08.017 db/journals/dam/dam157.html#ChandlerCKLP09