2kristilabrie
You can see which data sources LibraryThing has Z39.50 access to from the "Add books" page (https://www.librarything.com/addbooks), if that's what you're asking? Just click to "Add from 4,967 sources" to access them.
3navistar96
>2 kristilabrie: correct, they list a number of libraries. i assume the listed libraries accept a z39.50 connection.
4davidgn
>3 navistar96: True in over 99% of cases. There are a few hand-coded exceptions. If we ever get proper SRU support finished, that will shift the numbers slightly.
5navistar96
the LibraryThing data sources (z39.50) appear to have their url's hidden.
6bnielsen
>5 navistar96: In some cases you need username/password authentication too. And if the url for the Z39.50 connection is not listed on the library's own webpages it is probably on purpose, so LibraryThing shouldn't list it either.