How do you deal with 'fact cards'?

I know that the Zettelkasten method is ideally only about original thoughts, but sometimes, it's good to keep a fact or a statistic on hand when relevant to the content around it. We can usually go back to the source (although I'm trying to be better about using libraries and not storing endless books in my tiny house). Still, sometimes I find it helpful to keep the fact in the Zettelkasten.

I've been writing facts like this on their own single note card, and then following it with linked cards asking questions about the facts, or explaining why I think it's relevant.

It works for me, but what do you do?