1. Annexstein, F., Berman, K.: Directional routing via generalized st-numberings. Discrete Mathematics 13, 268–279 (2000)
2. Battista, G.D., Eades, P., Tamassia, R., Tollis, I.G.: Graph Drawing: Algorithms for the Visualization of Graphs. Prentice Hall, Englewood Cliffs (1999)
3. Even, S., Tarjan, R.E.: Computing an st-Numbering. Theoretical Computer Science 2, 339–344 (1976)
4. Gallai, T.: On directed paths and circuits. In: Theory of Graphs: International Symposium, pp. 215–232 (1968)
5. Garey, M.R., Johnson, D.S.: Computers and Intractability; A Guide to the Theory of NP-Completeness. W. H. Freeman & Co., New York (1990)