The reason for citing your sources is to give credit to those authors whose ideas you used in your research. Even when you do not quote directly from another work, if reading that source contributed to the ideas presented in your paper, you should include it in your bibliography. If you do not cite the source, you may be guilty of plagiarism. Plagiarism is using the ideas and writings of others and representing them as your own.
The two most common guides for citing sources are MLA (Modern Language Association, commonly used in the humanities) and APA (American Psychological Association, commonly used in the social sciences and sciences). You also may encounter Chicago, Turabian, or other styles. Ask your professor which style he or she prefers.
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