(from preface)

This volume makes a major contribution to the process of up-dating earlier volumes that we have initiated. Seven of the nine chapters are devoted to this purpose and from now on we intend to up-date chapters from 10 to 15 years after their appearance, provided that considerable work has been carried out in the area covered.
Five chapters have been up-dated by the authors of the original chapters that appeared in earlier volumes, as follows: Quinazolines, by W. L. F. Armarego (the original chapter appeared in Volume 1), Three-membered Rings with Two Heteroatoms, by E. Schmitz (Volume 2), Physicochemical Aspects of Purines, by J. H. Lister (Volume 6), Reis-sert Compounds, by F. D. Popp (Volume 9), and Pyridazines, by M. Tiffler and B. Stanovnik (Volume 9).
Two other chapters up-date subjects covered in earlier volumes, but by different authors: Selenium-Nitrogen Heterocycles, by I. Lalezari, A. Shafiee, and M. Yalpani, which up-dates the contribution by Bulka in Volume 2 on Selenazole Chemistry, and Pyrrolizidines, by D. J. Robins, which up-dates the contribution by Kochetkov and Likhosherstov in Volume 5.
Finally, two chapters deal with substantially new topics: Benzo[c]cin-nolines, by J. W. Barton, and 1, 4-Thiazines, by R. J. Stoodley.