1. J. Edmonds, Edge-disjoint branchings, to appear.
2. Two theorems on pseudosymmetric graphs;Gupta;SIAM J. Appl. Math.,1967
3. Beitrag zur Theorie der endlichen gerichteten Graphen;Kotzig;Wiss. Z. Martin-Luther-Univ. Halle-Wittenberg, Math.-Natur. Reihe,1961
4. Pseudosymmetry, circuit-symmetry and path-symmetry of a digraph;Simões-Pereira,1969