Hmmm slightly puzzled...
I'm writing my dissertation right now, and found a lot of good book chapters in CambridgeCore that I had access to in November. I saved them as PDFs and wrote my bibliography, but when I click the stable URLs that I saved, they're invalid.
I can see the chapters are still on cambridge core, but my institution no longer has access to them.
Can I still cite them? No idea how I'd even link them. Maybe link to their public interface pages.