Reports: Sort by Landing Page Ref

[Tech11]

Hi,

If you go to online reports (https://example.myshopify.com/admin/reports/sessions_by_landing_page  or  https://example.myshopify.com/admin/reports/online_store_conversion), there are filters that can be used to narrow down on data.

Our goal is see where the the traffic came from (using ref=source), which, as I understand would be the 'Landing Page Ref.' However, there is no filter for Landing Page Ref (the closest being Landing Page URL, which does not work since checkout pages URL change).

Can someone please advise as to how we can track this? 

Thanks!