1. Digraphs: Theory, Algorithms and Applications;Bang-Jensen,2000
2. Graphs;Berge,1989
3. Perfect graphs kernels and cores of cooperative games;Boros;Discrete Math. 306,2006
4. V. Chhvátal, On the computational complexity of finding a kernel. Report CRM300 Université de Montréal, Centre de Recherches Mathématiques, 1973
5. A note on kernel-critical graphs;Ducher;Discrete Math.,1981