The Demigod Files is a book by Rick Riordan that provides a guide to the series of Percy Jackson novels.
The release date of this book was February 10, 2009.
The Demigod Files book description
How do you handle an encounter with Medusa on the New Jersey interstate?
What’s the best way to take down a minotaur?
Become an expert on everything in Percy’s world with this must-have guide to the Percy Jackson and the Olympians series.
Complete with interviews, puzzles, games, and original short stories by Rick Riordan.