This study is based on 40 years interest in the area and is written by the Oman expert, Joachim Duester. Although centered on official envelopes used by a rebel group for distributing their stamps and propaganda, it also provides an overview of the history of Oman which forms the background of the stamp issues, the 'legal' framework for the postal use of the rebel stamps, and the personalities involved. It also has an extensive bibliography of all references known to the author relating to State of Oman and Dhufar stamp issues. The key part, though, is a catalogue of the official envelopes. The book is thoroughly illustrated (in black and white, and colour), and very thoroughly categorised. Dates of use for First Day Covers (and the stamps used for this purpose) and ordinary mailings are provided. This book is important for everyone interested in the postal history (and even just the history) of Muscat and Oman. It is also of great interest to those concerned with Arabian Gulf Postal History.