What has the author G M Sifakis written?

It seems you're asking about an author named "G M Sifakis". However, there is no widely recognized author with that exact name. It's possible:

* There's a typo: Check the spelling carefully. Is it "G.M. Sifakis" or perhaps a different variation?

* The author is not well-known: They might be a newer author, writing in a niche genre, or using a pen name.

To help me find the correct author, please provide more details if you have them:

* Full name: If you have the full name, even if it's slightly different from "G M Sifakis."

* Genre: What kind of books does the author write? (e.g., fiction, non-fiction, science fiction, etc.)

* Titles: Do you know any specific book titles by this author?

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