Litwack, L. F. (1961). North of slavery: The Negro in the free States, 1790-1860. University of Chicago Press.
Cita Chicago (17th ed.)Litwack, Leon F. North of Slavery: The Negro in the Free States, 1790-1860. [Chicago]: University of Chicago Press, 1961.
Cita MLA (9th ed.)Litwack, Leon F. North of Slavery: The Negro in the Free States, 1790-1860. University of Chicago Press, 1961.
Atenció: Aquestes cites poden no estar 100% correctes.