Citing the sources you use is important, because if you draw upon other people's work in your writing and research and do not acknowledge those sources, you can be accused of plagiarism. Citations also allow your readers to follow up sources you have referred to enabling the sharing of ideas. More information on why citing is important.
All scholarship builds upon the work of others. When you use the work of others, you must acknowledge it appropriately for several reasons:
(Academic Skills Unit, 2013).
For a guide to the available software, have a look at Managing References