The Chicago Manual of Style by Zotero is a free citation/reference resource management software. It can be run as a stand-alone application on your computer or managed online. Once you've installed the browser extension, Zotero automatically interprets data on a web site, and with a click, adds a record to your library.
Click on items from:
...and Zotero creates a citation record of the item along with a direct URL link and available PDF files.
Click for a detailed Guide to Using Zotero