You have an article in PDF format and maybe would like to put some of the references into a program such as Endnote, or perhaps quickly get some of them in full text, or find related articles etc etc. What to do?
A good option is to copy the references from the PDF and paste them into the box at http://www.hubmed.org/citation.htm and Submit. If they have all split ok then say Yes. On the resulting page you might have to delete some that aren’t found by most seem to be found ok so then click Done. Now you can easily find the citations on Google Scholar, export to a variety of citation managers