Mong-Jen Kao Bastian Katz Marcus Krug D. T. Lee Ignaz Rutter Dorothea Wagner The Density Maximization Problem in Graphs. 25-36 2011 COCOON http://dx.doi.org/10.1007/978-3-642-22685-4_3 conf/cocoon/2011 db/conf/cocoon/cocoon2011.html#KaoKKLRW11