You can use the Find Full Text feature to assist in locating the full articles of your references.
You can search for up to 250 references at one time.
For best results:
The Find Full Text tool can be used to locate and attach PDFs and web addresses for your references.
To get the best results, set up the Preferences:
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Watch EndNote 20: Find Full Text tool (YouTube, 1m24s)
Note: Some providers are known to have limited success in returning results e.g. EBSCO, JSTOR, ScienceDirect, and Wiley.
Other options to try include: