1. Berge, C.,Théorie des graphes et ses applications (Paris, Dunod 1958).
2. Guy, R. K.,Unsolved Combinatorial Problems, Combinatorial Mathematics and its Applications, in Proc. Confer. Oxford 1969 (Academic Press, N. Y. 1971), pp. 121–127.
3. Hall, M. Jr.,Combinatorial Theory (Ginn-Blaisdell, Waltham, Mass. 1967).
4. Hell, P. andRosa, A.,Graph Decompositions, Handcuffed Prisoners and Balanced P-designs, Discrete Math.2, 229–252 (1972).
5. König, D.,Theorie der endlichen Graphen (Leipzig 1936).