In July 2016, a Louisiana Hell note collector got in touch to show me some of the treasures from his 2,500-strong hoard.
I've reproduced my favourites from his scans here, and this is what he told me about them:
"Older notes often look a lot like Chinese money of the same era. Hell notes are seldom dated, but one of these is ... on the back. The date is 1928, but it may or may not actually have been made then. Notice the cool train picture.
"The two vertical notes are unusual. One resembles the gold and other currency certificates issued by Taiwan in real currency. The other captures some of the history of China with representations of old Chinese cash coins.
"Correctly speaking, these 'coins' are inscribed as charms. But it is certainly an intriguing note. It is also somewhat unusual in that it is one-sided.
"The last one is a small note picturing Joseph Stalin. A whole series of these flooded the market during the Vietnam war era. They mimic actual Hell notes in the wording, but picture various personalities like JFK, Eisenhower and Marilyn Monroe.
"They are not regarded as real Hell notes but rather were a kind of Vietnamese joke. There are some legitimate Hell notes of the same design featuring the King of the Underworld in the centre.
"Vietnam is the source for many of the modern Hell note issues. I included this note because the series is so ubiquitous and is often described as rare. It is far from rare.
"Such personalities would never have been put on real Hell notes, as we need to understand that they are used for sacred purposes in the exercise of religion. Who would want to send money to Joseph Stalin in the afterlife?"
* Many of the notes here are based closely on real banknotes. You can see a real 100 euro banknote here and a real 1,000 rouble note here.