What has the author Gertrude Armbruster written?

There is no widely known author named Gertrude Armbruster. It's possible you are thinking of a different name, or perhaps this is a lesser-known author.

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* Any other information about the author: Do you know their full name, their approximate time period, or the type of books they wrote?

* The book title: If you know the title of the book, it might be easier to find the author.

With more information, I can try to find the author you're looking for.