Omar Khayyam, Edward FitzGerald, Christopher Decker (1997). “Edward FitzGerald, Rubáiyát of Omar Khayyám: A Critical Edition”, p.174, University of Virginia Press
Sukarno's speech at the opening of the Bandung Conference, as quoted in "Selected Documents: Some Aspects Concerning Progress & Principles of the Indonesian Revolution, Book 1" (p. 14), April 18, 1955.
Frederick Douglass (2017). “FREDERICK DOUGLASS’ NARRATIVE – Memoirs of an American Slave, Freedom Fighter & Statesman: Narrative of the Life of Frederick Douglass, an American Slave & My Bondage and My Freedom”, p.98, e-artnow
"The American Soul: An Appreciation of the Four Greatest Americans and their Lessons for Present Americans". Book by Charles Sherwood Farriss, p. 63, 1920.