Using a citation manager will help you collect, organize, and cite the journal articles, books, websites, and other resources you consult when writing a paper. There are many, many citation management tools available. This guide discusses Zotero, a long-established, free, open source tool.
You can learn more about citations in general from this guide.
Zotero is an established, open source, and free citation manager. Its browser plugin (available for Chrome and Firefox) allows you to automatically save resources as you search and view them online. Zotero integrates with Microsoft Word, LibreOffice, and Google Docs to allow you to easily insert citations while you're writing your paper and automatically generate a bibliography or works cited page. You’ll need to download the Zotero desktop application to use its other features.
Zotero’s desktop application is available for Windows, Mac OSX, and Linux.