O'Reilly is a well known political commentator on a major cable news network. He is also an established author. His Killing series books are researched, historical narratives that do not lean politically in one direction or another. I found them to be very interesting books that broadened my knowledge and interest in new subject areas.
I hope you find them interesting too. You can find these books at your local library or if you prefer you can purchase them in print or electronic format.