The fourth Volume (‘Clandestine Radio’) in the Wireless for the Warrior series is different in approach to the previous books. Although it still contains a mix of technical data, photographs, line drawings and circuit diagrams, no extensive descriptions are provided, principally to limit the number of pages but also for reasons of non-availability of detailed information for the majority of the sets. This Volume is a combined effort of Louis Meulstee, Rudolf Staritz and a number of other authors, notably Jan Bury, Erling Langemyr, Tor Marthinsen, Pete McCollum and Antero Tanninen, experts in their own fields and living in various parts of the world. The time period imposed on the selection of sets to be included in this volume stretches from about 1938 up to the early 1990s, approximately to the fall of the Berlin Wall. It must be noted that apart from Clandestine, Agents or 'Spy' radio equipment, sets which were used by Special Forces, Partisans, Resistance, 'Stay Behind' organisations, Australian Coast Watchers and Diplomatic Service are covered. Also included are selected associated power sources, intercept receivers, RDF equipment, High speed keyers, S-Phone, bugs and radio- and radar beacons such as Eureka/Rebecca. In the Appendix there is a list of abbreviations. Volume 4 is covered in a number of main chapters, describing equipment used or manufactured in a certain country. Information is included on more than 230 sets. It contains 692 pages in A4 hardback format, and features over 850 photographs, 360 line drawings and 440 data tables