Zeppelin L-4 crashes into North Sea. (2013). The History Channel website. Retrieved 10:18, May 21, 2013, from http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea.
Zeppelin L-4 crashes into North Sea. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea [Accessed 21 May 2013].
“Zeppelin L-4 crashes into North Sea.” 2013. The History Channel website. May 21 2013, 10:18 http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea.
“Zeppelin L-4 crashes into North Sea,” The History Channel website, 2013, http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea [accessed May 21, 2013].
“Zeppelin L-4 crashes into North Sea,” The History Channel website, http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea (accessed May 21, 2013).
Zeppelin L-4 crashes into North Sea [Internet]. The History Channel website; 2013 [cited 2013 May 21] Available from: http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea.
Zeppelin L-4 crashes into North Sea, http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea (last visited May 21, 2013).
Zeppelin L-4 crashes into North Sea. The History Channel website. 2013. Available at: http://www.history.com/this-day-in-history/zeppelin-l-4-crashes-into-north-sea. Accessed May 21, 2013.