zotero, very neat Firefox extension. It helps one to find and track bibliography references from the web and unlike one of the web-based services, it keeps the data on your hard drive.
Find it at: http://www.zotero.org/
or at: https://addons.mozilla.org/en-US/firefox/addon/3504
With the move to the new extension method in firefox 57 i.e. quantum, the old extension doesn’t work any longer. Please find the Zotero connector at https://www.zotero.org/download/.
For a list of other useful extensions and alternatives that work with the new browser version, you may wish to look here: