Karen Aardal Stan P. M. van Hoesel Arie M. C. A. Koster Carlo Mannino Antonio Sassano Models and solution techniques for frequency assignment problems. 79-129 2007 153 Annals OR 1 http://dx.doi.org/10.1007/s10479-007-0178-0 db/journals/anor/anor153.html#AardalHKMS07