Soviet Union intervenes in Czechoslovakia. (2013). The History Channel website. Retrieved 12:28, May 21, 2013, from http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia.
Soviet Union intervenes in Czechoslovakia. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia [Accessed 21 May 2013].
“Soviet Union intervenes in Czechoslovakia.” 2013. The History Channel website. May 21 2013, 12:28 http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia.
“Soviet Union intervenes in Czechoslovakia,” The History Channel website, 2013, http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia [accessed May 21, 2013].
“Soviet Union intervenes in Czechoslovakia,” The History Channel website, http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia (accessed May 21, 2013).
Soviet Union intervenes in Czechoslovakia [Internet]. The History Channel website; 2013 [cited 2013 May 21] Available from: http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia.
Soviet Union intervenes in Czechoslovakia, http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia (last visited May 21, 2013).
Soviet Union intervenes in Czechoslovakia. The History Channel website. 2013. Available at: http://www.history.com/this-day-in-history/soviet-union-intervenes-in-czechoslovakia. Accessed May 21, 2013.