I use BibDesk, a great open-source reference management software package, with the help of Zotero and Zot2Bib, as described in the thread Lit & Note storing in DT and external Bib-Manager. If you use BibDesk (or are considering using BibDesk) you may be interested in the threads: How to index individual BibDesk entries in DEVONthink and Bibdesk keywords => MacOS tags ≠> Devonthink tags.