With citation management tools, you can store and organize citations downloaded directly from the online library catalog and most Library databases.  The History, Philosophy, and Newspaper Library recommends Zotero. 

Zotero is a powerful, easy-to-use citation manager and footnote/bibliography generator. It was developed by historians to support historical research. Zotero software and all of the files are located on your hard drive and can be set up to simultaneously sync to cloud storage, so you can access your sources wherever you're working. A special plug-in allows you to insert formatted footnotes and bibliographies into MS Word.