APA-ийн эшлэл(7 дахь хэвлэлт)

Soike, L. J. (2013). Necessary courage: Iowa's Underground Railroad in the struggle against slavery. University of Iowa Press.

Чикаго-гийн эшлэл (17 дахь хэвлэлт)

Soike, Lowell J. Necessary Courage: Iowa's Underground Railroad in the Struggle Against Slavery. Iowa City: University of Iowa Press, 2013.

MLA -ийн эшлэл (9 дэх хэвлэлт)

Soike, Lowell J. Necessary Courage: Iowa's Underground Railroad in the Struggle Against Slavery. University of Iowa Press, 2013.