It can be inquired by title, author, publisher, and year of publication.
The EGCC closed its doors 1.5 years ago and the library was moved elsewhere (or rather, what was left after removing all duplicates).
Do you know where it was moved to?
The library of the Dutch go association was moved to https://www.tresoar.nl/. But it doesn’t seem to be categorized by them yet.
On second thought, I’m actually not sure about any European Go Library (managed by Theo van Ees?), if it was really distinct from the Dutch go library or what happened to it. I saw only 1 library when I helped clearing the building.