Cédric Bentz Marie-Christine Costa Frédéric Roupin Maximum integer multiflow and minimum multicut problems in two-sided uniform grid graphs. 36-54 2007 5 J. Discrete Algorithms 1 http://dx.doi.org/10.1016/j.jda.2006.03.009 db/journals/jda/jda5.html#BentzCR07