W. E. B. Du Bois (2014). “Black Folk Then and Now (The Oxford W.E.B. Du Bois): An Essay in the History and Sociology of the Negro Race”, p.174, Oxford University Press
W. E. B. Du Bois (2014). “The Problem of the Color Line at the Turn of the Twentieth Century: The Essential Early Essays”, p.220, Oxford University Press
W. E. B. Du Bois (2013). “Black Reconstruction in America: Toward a History of the Part Which Black Folk Played in the Attempt to Reconstruct Democracy in America, 1860-1880”, p.13, Transaction Publishers