Tree Elaboration Strategies in Branch-and-Bound Algorithms for Solving the Quadratic Assignment Problem Peter M. Hahn, William L. Hightower, Terri Anne Johnson, Monique Guignard-Spielberg, Catherine Roucairol (2001) The Yugoslav Journal of Operations Research
Two-radially maximal graphs with special centers Ferdinand Gliviak, Martin Knor, Ľubomír Šoltés (1995) Mathematica Slovaca