* Topological approach to the chemistry of conjugated molecules, by A. Graovac, I. Gutman, and N. Trinajstic, Lecture Notes in Chemistry, no.4, Springer-Verlag, Berlin, 1977.
* Topological approach to the chemistry of conjugated molecules, by A. Graovac, I. Gutman, and N. Trinajstic, Lecture Notes in Chemistry, no.4, Springer-Verlag, Berlin, 1977.