George Carlin (2015). “3 x Carlin: An Orgy of George including Brain Droppings, Napalm and Silly Putty, and When Will Jesus Bring the Pork Chops?”, p.198, Hachette UK
William Penn (1807). “Fruits of solitude in reflections and maxims relating to the conduct of human life: Also, his advice to his children relating to their civil and religious conduct, to which are added extracts from the writings of William Law & Judge Hale; with a "Description of the happy man & true gentleman."”, p.92