Citation management systems allow you to download citations from various websites and databases (sometimes with the full-text article), electronically store and organize the citations as well as insert citations and a bibliography into your paper in the format of your choice as you write your paper. If you need to manage a large number of citations or are going to need to write a lot of papers that require you to cite sources, a citation management system may make citing sources in your paper a whole lot easier.

Here are some citation management systems you can use:

• Noodletools: a free tool to current DU students that collects, manages and cites sources.
• Zotero: is a free tool that collects, manages, and cites research sources.
• Mendeley: a free reference manager and academic social network.

If you're looking for a lightweight tool to just format individual citations, take a look at citation generators like ZoteroBib or Noodletools Express.