Regarding radio, it is important to keep in mind that Germany has a dual system of broadcasters (both TV and radio): There are private stations which generate revenues from commercials, and there are semi-public authorities which operate TV and radio stations. These were set up by the states (there is no federal competence in broadcasting), are governed by independent administrative boards and funded by a combination of broadcasting ads and collecting license fees which every owner of a TV or radio set has to pay.
All in all, there are nine such authorities in Germany (there are 16 states, but several states have decided to set up a common authority for their territories). Each one of these operates at least one TV channel and a variety, usually about five, radio stations. Hence, there is quite a large number of regional centers of radio broadcasting; the largest of these bodies are the WDR in the Western states of Germany, headquartered in Cologne, and the BR in Bavaria, headquartered in Munich.
Private radio stations usually don’t operate on the federal level either, but serve regional sectors.
Book publishing is much more centralized. There’s a variety of publishing companies, but most of them have been taken over by large media corporations. The most important ones are Bertelsmann in Guetersloh (an otherwise rather unimportant town in the North East of Cologne), Holtzbrinck in Stuttgart in the South West, Springer in Berlin, and dtv in Munich.