The last time I checked, Waiting for Godot was a play, which is to say fiction. Swift's "Modest Proposal" is an essay, not a book. A good many of the choices seem bien pensant. And are people still reading Dr. Spock? I gather poetry is thought to be non-fiction, which would surprise Wallace Stevens. Still, there are many fine choices (e.g., Travels With a Donkey, The Varietoes of Religious Experience).