(from preface)

The ninth volume of Advances in Heterocyclic Chemistry includes surveys of the chemistry of the following groups of heterocyclic compounds: 1,2,5-thiadiazoles (L. M. Weinstock and P. I. Pollack); 1,3,4-thiadiazoles (J. Sandstrom); pyridazines (M. Tisler and B. Stanovnik); Reissert compounds (F. D. Popp); phenothiazines (C. Bodea and I. Silberg); and pyrrolopyridines (R. E. Willette).
Suggestions are welcomed for contributions to future volumes; they should be in the form of short synopses.
Thanks are due to the Editorial Board, the publisher, and the authors for their cooperation.