© 2016 Mikkel Kristiansen. Dette værk er under en Creative Commons Navngivelse 4.0 International licens. Besøg http://creativecommons.org/licenses/by/4.0/ for at se en kopi af licensen. Eksternt materiale i form af linkede artikler, opgaver o.lign, se de respektive sider for deres ophavrettigheder.

By William Still - The underground rail road. A record of facts, authentic narratives, letters, &c., narrating the hardships, hair-breadth escapes, and death struggles of the slaves in their efforts for freedom, as related by themselves and others, or witnessed by the author; together with sketches of some of the largest stockholders, and most liberal aiders and advisers, of the road. (Available from archive.org.), Public Domain, https://commons.wikimedia.org/w/index.php?curid=34789588

By E. Hergesheimer (cartographer), Th. Leonhardt (engraver) - United States Coast Survey’s map of the slaveholding states, Public Domain, https://commons.wikimedia.org/w/index.php?curid=12273096