This item is not listed in Threads of History and in fact I have never seen another example.  The silk broadside is mounted on thick cardboard which has some age to it. The goal for this old method of preservation was reached as the broadside only has a few tiny edge problems, hardly worth mentioning.  Normally when you see something old mounted in this manner there is some acidic toning from the board.  This is not the case with the broadside and while I would not recommend this process for anything it did save the item from the stress of hanging which often causes separations in silk items.