1. Graphs and Hypergraphs;Berge,1973
2. On the computational complexity of finding a kernel;Chvátal,1973
3. Complexity of problems in games, graphs and algebraic equations;Fraenkel;Discrete Applied Math,1979
4. Computers and Intractability: A Guide to the Theory of NP-Completeness;Garey,1979
5. Some simplified NP-complete problems;Garey;Theoret. Comput. Sci,1976