American Railroad. (2013). The History Channel website. Retrieved 1:02, May 20, 2013, from http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives.
American Railroad. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives [Accessed 20 May 2013].
“American Railroad.” 2013. The History Channel website. May 20 2013, 1:02 http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives.
“American Railroad,” The History Channel website, 2013, http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives [accessed May 20, 2013].
“American Railroad,” The History Channel website, http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives (accessed May 20, 2013).
American Railroad [Internet]. The History Channel website; 2013 [cited 2013 May 20] Available from: http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives.
American Railroad, http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives (last visited May 20, 2013).
American Railroad. The History Channel website. 2013. Available at: http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/playlists/web-exclusives. Accessed May 20, 2013.