A citation is the information needed to identify a resource: a book, article, Web site, etc. Citations are included in bibliographies or works cited statements at the end of books, book chapters, articles and research papers. It is important to acknowledge your sources as accurately as possible so that readers can consult the articles and books that you used in your research.
Perhaps even more important though, citing a source is a way of participating in an “intellectual conversation” and is a way for “you to demonstrate your link to the community in which you work.”
Every time you cite a source, whether it's a book or a conference paper or a scholarly article or even a blog post, it needs to be documented in a list of references at the end of your paper. Depending on which citation style you are asked to use, this information might take a variety of forms. However, all styles of citation require the same key information: names of authors and/or editors; titles of articles, chapters, books, papers, etc; page or paragraph numbers; volume number; and dates of publication. How this information is arranged is dictated by the rules of citation styles.
Two of the main citation styles used by professionals in your field are ACS (American Chemical Society) and IEEE (Institute of Electrical and Electronics Engineers).
The main types of material you'll find yourself needing citations for are articles in periodicals, books and book chapters, conference papers, and technical reports.
Here are examples of a periodical reference in ACS style and IEEE style, respectively:
And here are examples of a book reference in ACS style and IEEE style: