Previous page or reffer url in worpress

Is there any method to get the previous page /refer page url in wordpress.

In my wordpress site there is a paypal form it include return url . So after payment complete it come back to the site. Now i need to check this page is returned from paypal website, not the user manually taken this page.

How to check this? Is there any function?

Any suggestions?

wp_get_referer() 

function will give you a referrer page URL.
codex documentation here