How to link a pdf from another location in your exposition.
The important thing is to resist the urge to link directly to the url of the pdf (displayed when it is opened), the url is not guarenteed to exists forever, because of access/permission control. It is therefore better to:
1. Organise your pdfs in a vertical list, for example on a new page. With enough whitespace in between to avoid confusion.
2. Retrieve the pdfs position:
a) scroll to the pdf tools position in the editor
b) commands tab->show current positition
3. Use these links to create hyperlinks.