The `org-ref` package contains this functionality. Contrary to the name, `org-ref` has a lot of functionality outside of org mode. Take a look at the function `org-ref-format-bibtex-entry`. It also integrates this into `helm-bibtex`, so if you get everything set up correctly, you can call `helm-bibtex`, mark the citations you want, then hit `f7` which inserts a formatted list.