1. Mathematische Unterhaltung und Spiele. II;Ahrens,1901-1918
2. On domination and some related topics in graph theory;Allan,1978
3. Mathematical Recreations and Problems of Past and Present Times;Rouse Ball,1892
4. The Theory of Graphs and its Applications;Berge,1958
5. The Theory of Graphs and its Applications;Berge,1962