# Zotero **URL:** [https://www.zotero.org/](https://www.zotero.org/) Sign-up required; free to use; paid subscription for syncing. --- Finding files without PDF attachments: - *Edit* > *Advanced search* > “Attachment File Type” “is not” “PDF” - *Save search* then brings the results of the search into the sidebar of your regular Zotero view (enabling you to interact properly with all the resulting files) --- See also: - ↬ [Better Bibtex for Zotero](https://retorque.re/zotero-better-bibtex/) - ↬ [Zotero hacks: unlimited synced storage and its smooth use with rmarkdown](https://ikashnitsky.phd/2019/zotero/)