45 books • 4 series
Stephen King's the Dark Tower: The Drawing of the Three Omnibus (Stephen King's the Dark Tower: The Drawing of the Three)
Stephen King's the Dark Tower: The Gunslinger Omnibus (Stephen King's the Dark Tower: The Gunslinger)
Stephen King's the Dark Tower: The Gunslinger (Stephen King's the Dark Tower: The Gunslinger)
Stephen King's the Dark Tower: Beginnings Omnibus (Stephen King's the Dark Tower: Beginnings)