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
Thomas Clarkson, William Penn (1827). “Memoirs of the private and public life of William Penn: who settled the state of Pennsylvania, and founded the city of Philadelphia”
Thomas Clarkson, William Penn (1827). “Memoirs of the private and public life of William Penn: who settled the state of Pennsylvania, and founded the city of Philadelphia”, p.124