1. Aho, A.V., Hopcroft, J.E., Ullman, J.D.: The design and analysis of computer algorithms. Reading, Mass.: Addison-Wesley 1974
2. Bays, C.: A non-recursive technique for re-creating a digraph from its K-formula representation. Computer J. 19, 4, 326?328 (1976)
3. Berztiss, A.T.: A backtrack procedure for isomorphism of directed graphs. J. ACM 20, 3, 365?377 (1973)
4. Berztiss, A.T.: Data structures: theory and practice. New York: 2nd ed. Academic Press 1975
5. Berztiss, A.T.: A very general data structure. Proc. International Comp. Symp. 1975, Taipei, Vol. 2, 138?145