有向非巡回グラフ
↑ Christofides, Nicos (1975), Graph theory: an algorithmic approach, Academic Press, pp. 170–174, ISBN 9780121743505 .
↑ Thulasiraman, K.; Swamy, M. N. S. (1992), “5.7 Acyclic Directed Graphs”, Graphs: Theory and Algorithms, John Wiley and Son, p. 118, ISBN 978-0-471-51356-8 .
↑ Bang-Jensen, Jørgen (2008), “2.1 Acyclic Digraphs”, Digraphs: Theory, Algorithms and Applications, Springer Monographs in Mathematics (2nd ed.), Springer-Verlag, pp. 32–34, ISBN 978-1-84800-997-4 .
↑ Thulasiraman, K.; Swamy, M. N. S. (1992), “5.7 Acyclic Directed Graphs”, Graphs: Theory and Algorithms, John Wiley and Son, p. 118, ISBN 978-0-471-51356-8 .
↑ Bang-Jensen, Jørgen (2008), “2.