14 books • 1 series
Book #1: Peter Grill and the Philosopher's Time Vol. 1
Book #2: Peter Grill and the Philosopher's Time Vol. 2
Book #3: Peter Grill and the Philosopher's Time Vol. 3
Book #4: Peter Grill and the Philosopher's Time Vol. 4
Book #5: Peter Grill and the Philosopher's Time Vol. 5