It is important to cite information when writing research papers, using other peoples ideas, when you are quoting others, and other instances. If you find yourself asking the question, "Should I cite this because I think it is common knowledge?," I would still go forth and cite the information anyways because it will not hurt. The last thing that you want to get in trouble for is plagiarizing someone else's material or information. Throughout undergraduate and graduate school they recommended that we buy the updated American Psychological Association (APA) manual. There is also a website that provides you with examples of APA papers (www.apa.org), there is a tutorial as well http://flash1r.apa.org/apastyle/basics/index.htm. Another website that will assist you with putting your references in APA format is Son of Citation Machine: http://citationmachine.net/. So the lesson of today is "When in Doubt, Cite Everything."