A citations generator needed
Web of Science allows you to extract (and even bulk-download) bibliographic metadata of scholarly works. (Select the papers, click on "Export...", choose "Other File Formats" and use "BibTeX" as File Format). 

Another option is JabRef, a reference manager which uses BibTeX and whose official browser extension "automatically identifies and extracts bibliographic information on websites and sends them to JabRef with one click."

I also find ZoteroBib useful. It worked well for me, and it is quick to use in browser.

Fur further options see Are there any tools to automatically search and download literature in a given .bib file?.