Are they using publicly accessible free resources on 'the internet' or library-focussed databases that aren't generally accessible to a person sitting at home?

Are they using publicly accessible free resources on 'the internet' or library-focussed databases that aren't generally accessible to a person sitting at home? Because I've never encountered a librarian that just uses 'the internet' to find out what books are available on a subject, they have specific databases at their disposal which are updated versions of the card-file of old, and those databases are not generally accessible to the public