Sometimes when you're trying to start a new project, especially a long project like a novel, the brain can get into a condition where the wheels spin but there's no forward progress. It's like getting stuck in the snow.
My tires got stuck in the snow when I started Rigel Kentaurus, my novel-in-progress. The novel is part of a large story-arc involving multiple alien races and a many-sided conflict. Think of it as part one of my opus magnum. The problem? I didn't know the alien race that plays a major role in this story. Not knowing this alien race was a show-stopper.
I needed fuel for the old brain, so from the shelf I pulled a book on Gothic history. This was in November of last year. It did the trick, and I know the aliens a lot better now, but it got me to thinking. How much reality is okay to lift? I'm borrowing Gothic words, Ancient European place names, and a mish-mash of Gothic, Hunnic, and Roman history. But now much of this is okay? How much can a writer use without changing names, words, and culture?
It's pretty clear that World War II had considerable influence on George Lucas and Star Wars. Stormtroopers--say no more.
So, it's something that a writer must consider. There will be readers who know where you got the information. Does it matter?
And by the way, if you've been to my web site, you probably noticed that Gothic history book still listed as "currently reading." I haven't forgotten to update the page, I've still got about 75 pages left.