Encyclopædia Britannica
Skolnik, Merrill I. "Radar." Encyclopædia Britannica. Chicago, IL: Encyclopædia Britannica, 2002. Encyclopædia Britannica. Encyclopædia Britannica. Web. 6 Apr. 2014. &lt;http://www.britannica.com/EBchecked/topic/488278/radar&gt;.