NYRB Classics reprinted Thomas Tryon’s 1971 bestseller "The Other" this month, a chilling story that sold millions of copies during its day, which was the decade of "Rosemary's Baby" and "The Exorcist." But of these three hair-raising novels, "The Other" unsettled me the most. Here's why. Also: An interesting database of 20th-century American Bestsellers book collectors will enjoy.