Different citation styles have specific elements that must be included in an encyclopedia citation. Typically, encyclopedia citations include some or all of the following elements.
Nisbet, Robert A. "Social Science." Encyclopaedia Britannica, 7 Jan. 2009,
https://www.britannica.com/topic/social-science.
Nisbet, Robert A. (2009). Social Science. In Encyclopaedia Britannica.
Retrieved from https://www.britannica.com/topic/social-science.
Nisbet, Robert A.. "Social Science.". Encyclopaedia Britannica. Last Modified January 7, 2009.