APA-referens (7:e uppl.)
Soike, L. J. (2013). Necessary courage: Iowa's Underground Railroad in the struggle against slavery. University of Iowa Press.
Chicago-referens (17:e uppl.)
Soike, Lowell J. Necessary Courage: Iowa's Underground Railroad in the Struggle Against Slavery. Iowa City: University of Iowa Press, 2013.
MLA-referens (9:e uppl.)
Soike, Lowell J. Necessary Courage: Iowa's Underground Railroad in the Struggle Against Slavery. University of Iowa Press, 2013.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.