How many books are in the Percy Jackson seris?

The five Percy Jackson books, in order, are:

Percy Jackson and the Lightning Thief

Percy Jackson and the Sea of Monsters

Percy Jackson and the Titan's Curse

Percy Jackson and the Battle of the Labyrinth

Percy Jackson and the last Olympian

There were 3 books updated after The Battle of The Labyrinth, Percy Jackson and The Olympians The Demigod Files, Percy Jackson and The Olympians Ultimate Guide, and Demigods and Monsters with an introduction by Rick Riordan.