Michele Conforti Gérard Cornuéjols Grigor Gasparyan Kristina Vuskovic Perfect Graphs, Partitionable Graphs and Cutsets. 19-33 2002 22 Combinatorica 1 http://link.springer.de/link/service/journals/00493/bibs/2022001/20220019.htm db/journals/combinatorica/combinatorica22.html#ConfortiCGV02