Let G be a Berge graph such that no induced subgraph is a 4-cycle or a line-graph of a bipartite
subdivision of K4. We show that every such graph G either is a complete graph or has an even pair.
Maria Chudnovsky, Frédéric Maffray, Paul Seymour, Sophie Spirkl
(2018).
Even pairs and prism corners in square-free Berge graphs. UWSpace.
http://hdl.handle.net/10012/18532