I do this exact same thing! If I write a new Zettel that references something I read in a book (for example), all I do is get the ISBN of the book (usually off of Amazon), use Zotero's auto-import feature, copy the reference and paste it into my note. The whole thing takes all of ~20 seconds, it's very efficient.
I know Zotero has a lot of other features, but 99% of my workflow with it is what I described above.
[0] https://www.lesswrong.com/posts/NfdHG6oHBJ8Qxc26s/the-zettel...