Likewise just because something is in print doesn't validate the material content, only the market niche for the content.
Why does this seem so far fetched to you? The Germans did also build the first ICBM during WWII. They also built TV guided anti-ship missiles that almost turned the tide of the Anzio landing.
Here are others:
Luftwaff Resource Center
German guided air to ground missiles
Just because you don't know about something doesn't mean it didn't happen. Dig in, you can find a lot. The best material, however, comes in printed books found in a library rather than on the web. Ever been to a library?
Just like publicly available government reports, right?