Bless you, Google Books !
This ad ran in the 19060705 (and subsequent) issue(s) of Geyer's Stationer
, a trade publication that featured industry news, along with advertorials & advertisements for pens, papers, office equipment and, yes, postcards for sale to stationery stores.
I will happily bet cash money that the inventor of the firecracker post cards is the great-grandfather of this moron:
Florida Deputy Mails Fake Bomb to Coworker, Evacuates Building, Resignshttps://blogs.findlaw.com/legalgrou...resigns.html