How to Find the Invoices Related to PO Number?

SELECT DISTINCT
a.org_id "ORG ID", 
e.segment1 "VENDOR NUM",
e.vendor_name "SUPPLIER NAME",
UPPER (e.vendor_type_lookup_code) "VENDOR TYPE",
f.vendor_site_code "VENDOR SITE CODE", 
f.address_line1 "ADDRESS",
f.city "CITY", 
f.country "COUNTRY",
TO_CHAR (TRUNC (d.creation_date)) "PO DATE", 
d.segment1 "PO NUM",
d.type_lookup_code "PO TYPE", 
c.quantity_ordered "QTY ORDERED",
c.quantity_cancelled "QTY CANCELLED", 
g1.quantity_received, 
g1.quantity_rejected, 
g1.quantity_billed,
g.item_id "ITEM ID",
g.item_description "ITEM DESCRIPTION", 
g.unit_price "UNIT PRICE",
(NVL (c.quantity_ordered, 0) - NVL (c.quantity_cancelled, 0))* NVL (g.unit_price, 0) "PO LINE AMOUNT",
(SELECT DECODE (ph.approved_flag, 'Y', 'Approved')
FROM po.po_headers_all ph
WHERE ph.po_header_id = d.po_header_id) "PO APPROVED?",
a.invoice_type_lookup_code "INVOICE TYPE",
a.invoice_amount "INVOICE AMOUNT",
TO_CHAR (TRUNC (a.invoice_date)) "INVOICE DATE",
a.invoice_num "INVOICE NUMBER",
(SELECT DECODE (x.match_status_flag,
'A', 'Approved'
)
FROM ap.ap_invoice_distributions_all x
WHERE x.invoice_distribution_id = b.invoice_distribution_id)"INVOICE APPROVED?",
a.amount_paid
FROM 
ap.ap_invoices_all a,
ap.ap_invoice_distributions_all b,
po.po_distributions_all c,
po.po_headers_all d,
ap.ap_suppliers e,
ap.ap_supplier_sites_all f,
po.po_lines_all g,
po.po_line_locations_all g1
WHERE a.invoice_id = b.invoice_id
AND b.po_distribution_id = c.po_distribution_id(+)
AND c.po_header_id = d.po_header_id(+)
AND e.vendor_id(+) = d.vendor_id
AND f.vendor_site_id(+) = d.vendor_site_id
AND d.po_header_id = g.po_header_id
AND g1.po_header_id = c.po_header_id
AND g1.po_line_id = g.po_line_id
AND c.po_line_id = g.po_line_id
AND c.line_location_id = g1.line_location_id
AND g1.inspection_required_flag = 'N'
AND g1.receipt_required_flag = 'N'