[1] AUSLANDER L., BROWN T. A., YOUNGS J. W. T.: The imbedding of a graph in manifolds. J. Math. Mech. 12, 1963, 629-634. MR 0151959

[2] FRANKLIN P.: A six color problem. J. Math. and Phys. 13, 1934, 363-369. Zbl 0010.27502

[3] RINGEL G.: The combinatorial map color theorem. J. Graph. Theory 1, 1977, 141-155. MR 0444509 | Zbl 0386.05030

[4] RINGEL G.: Non-existence of graph embeddings. (in Theory and Applications of Graphs, Proceedings, Y. Alavi and D. R. Lick eds.), LNM 642, Springer-Verlag, New York 1978, 465-476. MR 0499516 | Zbl 0398.05031

[5] STAHL S.: Generalized embedding schemes. J. Graph Theory 2, 1978, 41-52. MR 0485488 | Zbl 0396.05013

[6] STAHL S., BEINEKE L. W.: Blocks and the nonorientable genus of a graph. J. Graph Theory 1, 1977, 75-78. MR 0460165

[7] WHITE A. T.: Graphs, Groups and Surfaces. North Holland, London, 1984. MR 0780555 | Zbl 0551.05037

[8] WHITE A. T., BEINEKE L. W.: Topological graph theory. (in Selected Topics in Gгaph Theory), L. W. Beineke and R. J. Wilson eds.), Academic Press, London 1978, 15-50. MR 0543656 | Zbl 0439.05018

[9] YOUNGS J. W. T.: Minimal imbeddings and the genus of a graph. J. Math. Mech. 12, 1963, 303-315. MR 0145512 | Zbl 0109.41701