Not sure if "verso" is the correct term for the blank back which pops up quite often, sometimes with something hand written about the takings, or even a personal jotting. How to classify? Not a Playbill doesn't seem apt as it is a bill. Often on the thin paper some of the print on the front is readable in reverse. Both sides have been scanned, but usually not consecutively, so is it useful to try to cross-reference, if that is possible? I have been adding a note in Seen something interesting?, but there are a lot of them in the batch - Mark Titles: A collection of playbills from Theatre, King's Lynn 1764-1772.