1. Über eine Art von Graphen;Hajós;Internat. Math. Nachr.,1957
2. A characterization of comparability graphs and of interval graphs;Gilmore;Canad. J. Math.,1964
3. Representation of a finite graph by a set of intervals on the real line;Lekkerkerker;Fund. Math.,1962
4. Incidence matrices and intercal graphs;Fulkerson;Pacific J. Math.,1965
5. Indifference graphs;Roberts,1969