A citation...
describes a book, journal article, website, or other item
gives credit to the originator of an idea
enables the reader to access the cited item.
You must cite a source that you are using if you paraphrase or summarize any of the ideas given in the work AND if you use a direct quote from the resource (word-for-word). Citations are not just for word-for-word quotations; they must be used when you mention any ideas or information from a source.
The Owl/the Purdue Online Writing Lab (Purdue University) can help you with your writing assignments. Below is the website's navigation tab for all aspects covered.
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Mission
The Excelsior Online Writing Lab (Excelsior College) can help with your writing assignments. Below is the website's navigation tab listing every aspect covered.