Kazutoshi Ando Satoru Fujishige Toshio Nemoto Decomposition of a Bidirected Graph into Strongly Connected Components and Its Signed Poset Structure. 237-248 1996 68 Discrete Applied Mathematics 3 http://dx.doi.org/10.1016/0166-218X(95)00068-3 db/journals/dam/dam68.html#AndoFN96