Series
Percy Jackson ve Olimposlular
We don't know whether this one is finished.
Nobody has confirmed the status of this series yet. That's a gap in our data, not a verdict on the books.
2 books here
Publication order
This is publication order — nobody has confirmed a different reading order for this one yet.
4
The Battle of the Labyrinth
· Rick Riordan
5
The Last Olympian
· Rick Riordan