Litwack, L. F. (1961). North of slavery: The Negro in the free States, 1790-1860. University of Chicago Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रLitwack, Leon F. North of Slavery: The Negro in the Free States, 1790-1860. [Chicago]: University of Chicago Press, 1961.
एमएलए (9वां संस्करण) प्रशस्ति पत्रLitwack, Leon F. North of Slavery: The Negro in the Free States, 1790-1860. University of Chicago Press, 1961.
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