* The name is misspelled: There might be a very similar name that you're thinking of. Could you double-check the spelling?
* The author is relatively unknown: Perhaps Harry A Brandt is a less-known author who has written in a niche genre or only published independently.
* The author has published under a different name: Some authors use pen names, so it's possible this author has a different public identity.
To help me find the correct information, could you please tell me:
* What kind of books do you think Harry A Brandt might have written? (Genre, subject matter)
* Do you have any other information about the author? (Nationality, approximate time period of their work)
With more information, I can try to find relevant details about the author.