I always have thought that Osprey Publishing Ltd. of the U.K. was an excellent publisher of information especially designed for the historic wargamer and those with an interest in military history; they cover the whole range of the history of warfare, and they have numerous titles covering the Second World War.
I wouldn't call them specifically uniform information books, but each book contains about 5-6 double sided colored print illustrated drawings, in the main, based on actual photographs, with detailed notes and information about the uniforms the soldiers are wearing; each book also contains detailed historical information, and Osprey has different series of books, some focusing on specific campaigns, some specific battles like Stalingrad, and another on the various armies and individual infantry units involved.
The books, really booklets, because they average between 50 to 60 to 70 pages in length, are expensive, considering they are on on the shortside in length, averaging between $16.00 to $25.00 U.S. depending on the series.
You can usually find them at better hobby stores in the U.S.; a Borders Bookstore in my area has some of them (granted, it is a Borders located in one of the most upscale neighborhoods in town); I don't know if they have different language editions.
However, the price is worth it, considering that they are written usually by an expert military historian or expert of some sort, and contain great information and photographs.
See for yourself:
www.ospreypublishing.com
Also, Time-Life's WWII Series (published 1979) also is a good series to look at; there were about 20 or so books that dealt with the European and Pacific theaters, and they also had some books in the series dealing with special topics like resistance and partisan fighters. They are chock full of photographs and interesting information; you can probably find them at most public libraries in the United States.