: Open the file (if downloaded) and look at the "Properties" or "Metadata" for a DOI (Digital Object Identifier) or Title.
: If it is a figure, try a reverse image search on Google Images to find the original article. Download File 92BF0C95E3ADEFAA061B67DF491BA6EB8...
If you have the file itself or saw this on a download page, you can identify the source by: : Open the file (if downloaded) and look
