ayla said:Stamped on the inside of a handle.
http://cgi.ebay.com/100-AUTH-LOUIS-VUITTON-RED-BLK-Epi-PETIT-NOE-Bag_W0QQitemZ6872109889QQcategoryZ63852QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
(check last picture)
http://cgi.ebay.com/Louis-Vuitton-Gold-Epi-Petit-Noe-Larger-Shoulder-Bag-NR_W0QQitemZ6872090332QQcategoryZ63852QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
(another example)