Question: The Battle of the Labyrinth is the fourth novel in a pentalogy of adventure and mythological fiction books that have sold more than 45 million copies, and have been sold in how many countries?
Sentence (from "Percy Jackson &amp; the Olympians"): Percy Jackson & the Olympians, often shortened to Percy Jackson, is a pentalogy of adventure and mythological fiction books written by American author Rick Riordan, and the first book series in the Camp Half-Blood Chronicles.
Relevant evidence: Yes