[1] GROSS J. L., TUCKER T. W.: Topological Graph Theoгy. Wiley Interscience, New Yoгk 1987. MR 0898434

[2] LAS VERGNAS M.: Eulerian circuits of 4-valent graphs imbedded in surfaces. In: Algebraic Methods in Graph Theory, pp.451-477, Coll. Math. Soc. J. Bolyai 25, North-Holland, Amsterdam 1981. MR 0642057 | Zbl 0472.05043

[3] LINS S., RICHTER R., SHANK H.: The Gauss code problem off the plane. Aequationes Mathematicae 33, 1987, 81-95. MR 0901803 | Zbl 0591.05024

[4] PISANSKI T.: Orientable and non-orientable embeddings of graphs. PҺD. Thesis, Pennsylvania State University, University of Ljubljana 1981.

[5] PISANSKI T., MALNIČ A.: The diagonal construction and graph embeddings. Proc. of the Fourth Yugoslav Seminar on Graph Theory, Novi Sad 1983, 271-290. MR 0751455

[6] WHITE A. T.: Graphs, Groups and Surfaces. (second edition). North Holland, Amsterdam 1984. MR 0780555 | Zbl 0551.05037

[7] ŽELEZNÍK V.: Quadrilateгal embeddings of the conjunction of graphs. Math. Slovaca 38, 1988, 89-98. MR 0945362