Litwack, L. F. (1961). North of slavery: The Negro in the free States, 1790-1860. University of Chicago Press.
Chicago-čujuhus (17. p.)Litwack, Leon F. North of Slavery: The Negro in the Free States, 1790-1860. [Chicago]: University of Chicago Press, 1961.
MLA-čujuhus (9. p.)Litwack, Leon F. North of Slavery: The Negro in the Free States, 1790-1860. University of Chicago Press, 1961.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.