Hello,
Currently on ebay there is a nice photo of a Breguet AG 4 with a Deperdussin in the background at:
https://www.ebay.fr/itm/photo-aviati...sAAOSwrHNeypNT
Can anyone read the Breguet's serial number? BR.53 appears logical, at least I don't think its BR.52
Regards,
Clint