Andreas Brandstädt Feodor F. Dragan Victor Chepoi Vitaly I. Voloshin Dually Chordal Graphs. 437-455 1998 11 SIAM J. Discrete Math. 3 http://dx.doi.org/10.1137/S0895480193253415 db/journals/siamdm/siamdm11.html#BrandstadtDCV98