Access the QUICK_PO_NUMBER field from an invoice in the Database?

We need to create an invoice report and our stakeholders want the PO Number field from the invoice header section to be included.  When I examine the field it is in the INV_SUM_FOLDER block and the field name is QUICK_PO_NUMBER.  I have searched different tables in the database and cannot find the field anywhere.  Does anyone have any suggestions about where I can find this field (what table/view it might be found in).

We need to use this field instead of the line/distribution level ones after matching because the report is for unpaid/unmatched invoices so that PO link will not be there yet, but would be at the header level if entered by the user.