National Guard kills four at Kent State. (2013). The History Channel website. Retrieved 4:01, May 25, 2013, from http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state.
National Guard kills four at Kent State. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state [Accessed 25 May 2013].
“National Guard kills four at Kent State.” 2013. The History Channel website. May 25 2013, 4:01 http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state.
“National Guard kills four at Kent State,” The History Channel website, 2013, http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state [accessed May 25, 2013].
“National Guard kills four at Kent State,” The History Channel website, http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state (accessed May 25, 2013).
National Guard kills four at Kent State [Internet]. The History Channel website; 2013 [cited 2013 May 25] Available from: http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state.
National Guard kills four at Kent State, http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state (last visited May 25, 2013).
National Guard kills four at Kent State. The History Channel website. 2013. Available at: http://www.history.com/this-day-in-history/national-guard-kills-four-at-kent-state. Accessed May 25, 2013.