There are a few possibilities:
* Typo: Maybe there's a slight error in the name. Double check the spelling.
* Less known author: It's possible the author is less well-known or has published under a different name.
* Specific genre: Do you know what kind of books James H Averill might write? This can narrow the search.
If you can provide more information, I might be able to help you find more about this author.