Henry Mackenzie (1815). “The Works of Henry Mackenzie, Esq. ...: The man of feeling, and miscellaneous pieces.-v.II. The man of the world.-v.III. Julia de Roubigné”, p.192
Ralph Waldo Emerson, Alfred R. Ferguson (1965). “Journals and Miscellaneous Notebooks of Ralph Waldo Emerson, Volume V: 1835-1838”, p.335, Harvard University Press
Theodore Roosevelt (2015). “Theodore Roosevelt on Bravery: Lessons from the Most Courageous Leader of the Twentieth Century”, p.78, Skyhorse Publishing, Inc.
Will Rogers, Bryan B. Sterling (1995). “Will Rogers Speaks: Over 1,000 Timeless Quotations for Public Speakers (writers, Politicians, Comedians, Browsers ...)”, M Evans & Company