All three of these citation tools (Zotero, EndNote, and Mendeley) allow you to orgainize and store your references, as well as integrating with Microsoft Word to create in-text citations and bibliographies in various styles.  Which tool is best depends on your own needs and personal workflow.  

For more information see this comparison chart.  

• Zotero is a free Firefox extension that helps you collect, manage, and cite your research sources.
• EndNote is a comprehensive citation management tool that helps users search for, organize and cite bibliographic information.
• Mendeley is a free reference manager and academic social network that can help you organize your research library, collaborate with others online, and discover other relevant papers based on what you are reading.

Other citation tools such as (KnightCite, EasyBib, and more) are also available and may be helpful.

For requests for individual consultations or group trainings, contact the librarians listed on the guides above.