Historical clue formulations

• Debt notes — 2023-05-06
• Signed i.o.u.'s — 2021-02-28
• Possible poker payments — 2019-06-15
• Payment vouchers — 2019-03-31
• Markers — 2017-06-09
• Vouchers — 2016-12-30
• Signed notes — 2016-11-20
• Some poker payments — 2010-06-11
• I.O.U.'s — 2006-04-20
• Notes of a sort — 2001-07-08
• Signed I.O.U.'s — 2000-09-18
• Debt markers — 1997-11-04
• Some poker payments — 1997-05-18
• I.O.U.'s — 1996-11-11