1. S.A. Burr, Subtrees of directed graphs and hypergraphs, in: Proceedings of the Eleventh Southeastern Conference on Combinatorics, Graph theory and Computing, Florida Atlantic University, Boca Raton, FL, Vol. I, 28, 1980, pp. 227–239.
2. Functions and line digraphs;El Sahili;J. Graph Theory,2003
3. On directed paths and circuits;Gallai,1968
4. Oriented hamiltonian paths in tournaments;Havet;J. Combin. Theory Ser. B,2000
5. Embedding oriented n-trees in tournaments;Reid;Studia Sci. Math. Hungaria,1983