I don't honestly know myself. But please be very careful not to reprint articles to which we have no rights. If the article appears elsewhere on the web, it's always best to link to the original rather than copy it. Articles can also be saved as, for example, PDFs, and those can be uploaded.
OK, I'll try to remember about the copyright issue.
But how 'link'? The URLs within articles I have posted, don't seem to be clickable. Which seems to imply that readers will have to copy them and paste into Google's 'enter query to search'. Have I got this right?
And when you say
'Articles can also be saved as, for example, PDFs, and those can be uploaded'.
Ning allows rich text editing - simply highlight the text that should be a link, then click on the link icon above the box into which you are entering text.
And even if you did put in a full URL (starting with http) and it was not a link, why would you turn to Google? You'd copy and paste that into your browser's address bar.
Finally, PDF files that include illustrations are uploaded as is -- of course they include the illustrations.