If you want to make a page related to WikiProject The Simpsons featured (whether it is an article or a list), you have to apply sources to every piece of information. Any information given in an article should be verifiable by a reliable source. If you want to make a page featured you probably need at least 30 references. There is some confusion as to what proper sourcing is and therefore this guide is made to help you save time and go for the right source right away.
Even though IMDb seems like a valuable source for information it functions more or less the same way Wikipedia does. It gets its information from its users, which is then approved by the staff. Since the information comes from the users, the site fall under the criteria above and can not be considered a reliable source.
Now this one is going to hurt. The Simpsons Archive is simply the best source for information about The Simpsons, but the information is provided by its users and a newsgroup and on top of that does the website contain copyrighted material, which they have not got permission for. There is one way to use some of the material, which will be discussed later under "News articles" in the next section.
The show itself
The show itself is a primary source and thus can not be used for anything else but plot summaries. You can not use it for drawing conclusions.
DVD commentary: The DVD commentaries are truly valuable background information. Be aware that it is not enough to simply write Somewhere on the season 2 DVD commentary. Be specific and cite what episode the information comes from, so that the information can be verified.
News articles: These are usually solid information and sometimes go a bit deeper than the usual stuff. The Simpsons Archive contains a section with articles and interviews they have (illegally) transcribed. If we take this page for an example, you can still use it, because they have provided all the publishing details (By Judy Brennan, Los Angeles Times, March 3, 1995, p. F-18). If you reference the news paper directly and do not link to The Simpson Archive it is a perfectly valid reference.
Documentaries: There have been produced a couple of documentaries on the show. These can also be used.
Books: Paper sources are the best kind of source you can use. Over time people have been writing a few decent books. Below is a list of recommendations:
Alberti, John, ed. (2003). Leaving Springfield: 'The Simpsons' and the Possibility of Oppositional Culture. Wayne State University Press. ISBN0-8143-2849-0.
Brown, Alan; Chris Logan (2006). The Psychology of The Simpsons. Dallas, Texas: Benbella Books. ISBN1-932100-70-9.
Gray, Jonathan (2006). Watching with The Simpsons: Television, Parody, and Intertextuality. Abingdon: Routledge. ISBN0-4153-6202-4.
Irwin, William (2003). Mark T. Conard; Aeon Skoble (eds.). The Simpsons and Philosophy: The D'oh! of Homer. Chicago, Ill.: Open Court. ISBN0-8126-9433-3.
Turner, Chris (2004). Planet Simpson: How a Cartoon Masterpiece Documented an Era and Defined a Generation. Toronto: Random House Canada. ISBN0-679-31318-4.
Keller, Beth L. (1992). The Gospel According to Bart: Examining the Religious Elements of The Simpsons. Regent University. ISBN0-8126-9433-3.
Keslowitz, Steven (2004). The Simpsons And Society: An Analysis Of Our Favorite Family And Its Influence In Contemporary Society. Tucson: Hats Off Books. ISBN1-58736-253-8.
Pinsky, Mark I. (2001). The Gospel According to The Simpsons: The Spiritual Life of the World's Most Animated Family. Louisville: Westminster John Knox Press. ISBN0-664-22419-9.
Pinsky, Mark I.; Samuel F. Parvin (2002). The Gospel According to the Simpsons: Leaders Guide for Group Study. Louisville, KY: Westminster John Knox Press. ISBN0-664-22590-X.