World's Largest Combine. (2013). The History Channel website. Retrieved 6:39, May 23, 2013, from http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech.
World's Largest Combine. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech [Accessed 23 May 2013].
“World's Largest Combine.” 2013. The History Channel website. May 23 2013, 6:39 http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech.
“World's Largest Combine,” The History Channel website, 2013, http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech [accessed May 23, 2013].
“World's Largest Combine,” The History Channel website, http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech (accessed May 23, 2013).
World's Largest Combine [Internet]. The History Channel website; 2013 [cited 2013 May 23] Available from: http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech.
World's Largest Combine, http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech (last visited May 23, 2013).
World's Largest Combine. The History Channel website. 2013. Available at: http://www.history.com/shows/modern-marvels/videos/playlists/farming-tech. Accessed May 23, 2013.