Although our collecting interests land in many areas – from knives, to vehicles, to patches, to things that go bang – in the end, most collectors also enjoy books. If, like me, you own a WWII Jeep, you almost certainly own several books in the All American Wonder series, as well as The Complete WW2 Military Jeep Manual. You may also have issues of Army Motors, or technical manuals like The Motor Vehicle TM10-510 and Motor Transport Inspections TM10-545. A jeep owner could easily fill three feet of bookshelf with books related to jeeps.
If you collect WWII German documents, you probably have copies of Forman’s Guide to Third Reich German Documents… and Their Values (in several volumes), as well as Paper’s Please, by Ray & Josephine Cowdery, and several other books.
Home front collectors have by Brown, by Cohen, and by Adams-Graf.