5546 history grabbing bookmark

I need a script where: while a user is surfing the web, the user can click a bookmark to a particular page on my site. when the page on my site is reached, it gets the referring url and stores it in a variable (php or javascript is fine - php is preferred) This should ALWAYS work. I have not been able to get the url with HTTP_REFERER through a bookmark, but it's defnitely possible since other sites have these types of bookmarks. Need this ASAP