Keep in mind this handy rule of thumb:
"When in doubt, CITE IT!"
It is never wrong to cite something. If you ever find yourself in a situation where you are not sure if you need to cite particular information (is it common knowledge or not?), citie it. That is the safest thing to do.
When we speak of citing, two things are meant. The first is citing within the text of a paper, either by using parenthetical references, or footnotes. The second is providing complete bibliographic information for your sources in a bibliography (also known as a Works Cited page or Reference list).
The Duquesne University Writing Center has created very helpful guides to assist you with citing in-text and in bibliographies in MLA, APA, and Chicago Manual of Style. PDFs of these documents are available below.
Note: The information in the handouts refers to the outdated 7th edition MLA Handbook.
The Gumberg Library has also created a document that compares MLA and APA formats and gives more in-depth information on using them in bibliographies than does the DU Writing Center's "Reference List" document in the box above.
Surprisingly, not everything has to be cited. For example, a statement like "George Washington is known as the 'Father of His Country'" would not need to be cited because this is a general idea in the culture that most people are aware of. These sorts of information are called "common knowledge."
Another way to express this is, if three to five reference works all say the same thing about a topic, then that idea is common knowledge. It is not the intellectual property of any one individual, and, therefore, does not need to be cited. If you ever have questions on whether a statement is common knowledge, Ask a Librarian, talk to your professor, or contact the Duquesne University Writing Center.
Below is the link to the Duquesne Writing Center guide on developing paragraphs.