Theodore Roosevelt (2015). “Theodore Roosevelt on Bravery: Lessons from the Most Courageous Leader of the Twentieth Century”, p.14, Skyhorse Publishing, Inc.
William Shakespeare, Nick De Somogyi (2001). “Hamlet: The Tragedie of Hamlet, Prince of Denmarke : the First Folio of 1623 and a Parallel Modern Edition”, p.106, Nick Hern Books
Angelus Silesius, Frederick Franck (2005). “Messenger of the Heart: The Book of Angelus Silesius with Observations by the Ancient Zen Masters”, p.102, World Wisdom, Inc