1. J.E. Cohen, Interval graphs and food webs: A finding and a problem, RAND Corporation Document 17696-PR, Santa Monica, CA, 1968
2. Niche graphs;Cable;Discrete Appl. Math.,1989
3. Niche numbers;Fishburn;J. Graph Theory,1992
4. The competition number and its variants;Kim,1993
5. Competition numbers of graphs with a small number of triangles;Kim;Discrete Appl. Math.,1997