From the Internet:

Author Last Name, First. “Title of Cartoon.” Type of Cartoon. Name of Website. Publisher of Website, Publication Date. Medium of ______Publication. Day Month Year of your visit. <URL>.

Example:
Flintstone, Fred. “Abraham Lincoln.” Political Cartoon.  Cartoons Galore. History Museum, 2005. Web. 9 September 2010. _
______ <http://www.cartoonsgalore.com>.

From a Book:

Author Last Name, First. “Title of Cartoon.” Type of Cartoon. Name of Book. Publishing City: Publisher, Publication Date. Page #.
______ Medium of Publication.

Example:
Flintstone, Fred. “Abraham Lincoln.” Political Cartoon. The World of Politics. New York: Tops Publishing, 2009. 34. Print.

From a Newspaper:

Autho Last Name, First. “Title of Cartoon.” Type of Cartoon. Name of Newspaper [ Publishing City] Publication Date, section: page ______number. Medium of Publication.

Example:
Flintstone, Fred. “Abraham Lincoln.” Political Cartoon. Chicago Sun Times [Chicago] 5 September 2010, section B: 13. Print.