Ernst Rohm's address to Kurt Ludecke (January 1934), as quoted in H. Paul Jeffers "History's Greatest Conspiracies: One Hundred Plots, Real and Suspected, That have Shocked, Fascinated, and Sometimes Changed the World", August 1, 2004.
David Ricardo, John Ramsay McCulloch (1852). “The Works of David Ricardo. With a notice of the life and writings of the author: by J. R. McCulloch”, p.84