Nash, G. B. (1991). Freedom by degrees: Emancipation in Pennsylvania and its aftermath. Oxford University Press.
Lua i Stíl Chicago (17ú heag.)Nash, Gary B. Freedom by Degrees: Emancipation in Pennsylvania and Its Aftermath. New York: Oxford University Press, 1991.
Lua MLA (9ú heag.)Nash, Gary B. Freedom by Degrees: Emancipation in Pennsylvania and Its Aftermath. Oxford University Press, 1991.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.