Citation styles differ in format but are alike in their underlying principles. They provide a system to tell readers when information is borrowed and provide enough publishing information that readers can locate the original sources. All types of borrowing—quotes, paraphrases, and summaries—must be credited.
Check with your instructor for the recommended citation style for your subject area.
MLA (Modern Language Association) citation style requires you to note in the text of your paper every time you borrow information from a source, whether you quote, paraphrase, or summarize. In-text citations are brief and are used in conjunction with a Works Cited list with more complete information about your sources.
For more information consult Cite Your Sources: MLA Style.
The MLA Handbook, 9th edition, is the ultimate guide for using this citation style. The St. Martin's Handbook and credible online resources for using MLA citations are all based on the MLA Handbook. The library has two copies; ask for them at the Library Services desk.
MLA Handbook by APA (American Psychological Association) citation style requires you to note in the text of your paper every time you borrow information from a source, whether you quote, paraphrase, or summarize. In-text citations are brief and are used in conjunction with a References list with more complete information about your sources.
For more information consult: Cite Your Sources: APA Style.
The Publication Manual of the American Psychological Association is the ultimate source for using this citation style.
Publication Manual of the American Psychological Association by 
The Chicago Manual of Style by 
The ACS Style Guide by 