You can locate the full-text PDFs from JSTOR and drag and drop them into Mendeley. Mendeley does the rest! Alternatively, select citations of interest in JSTOR and click Export
click on the RIS file
save the .ris file
locate the RIS file and drag and drop into Mendeley desktop
and you are done. You can also locate the full-text PDFs from JSTOR and drag and drop them into Mendeley. Mendeley extracts the metadata from the PDF. However, you can also use the update fields feature (right click on the reference of interest in Mendeley to update) or you could manually add the missing information.