Charles Sumner. (2013). The History Channel website. Retrieved 12:54, May 25, 2013, from http://www.history.com/topics/charles-sumner.
Charles Sumner. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/topics/charles-sumner [Accessed 25 May 2013].
“Charles Sumner.” 2013. The History Channel website. May 25 2013, 12:54 http://www.history.com/topics/charles-sumner.
“Charles Sumner,” The History Channel website, 2013, http://www.history.com/topics/charles-sumner [accessed May 25, 2013].
“Charles Sumner,” The History Channel website, http://www.history.com/topics/charles-sumner (accessed May 25, 2013).
Charles Sumner [Internet]. The History Channel website; 2013 [cited 2013 May 25] Available from: http://www.history.com/topics/charles-sumner.
Charles Sumner, http://www.history.com/topics/charles-sumner (last visited May 25, 2013).
Charles Sumner. The History Channel website. 2013. Available at: http://www.history.com/topics/charles-sumner. Accessed May 25, 2013.