If you have a DOI, PMID, ISBN, or arXiv ID, it's easy to add it to Zotero.
1. Click the wand icon on the top menu of Zotero
2. Type or copy and paste the ISBN, DOI, PMID, or arXiv ID number into the search box and click enter
3. Using the ID number, Zotero will automatically search for your item and create an entry for you. If anything looks incorrect on the right hand side, simply click on the field and manually edit the error. Zotero will automatically save for you.