Historical clue formulations

• Minor mistakes — 2023-03-06
• Boo-boos — 2019-08-10
• Boo-boos — 2018-08-06
• Mistakes — 2015-01-25
• Goofs — 2009-12-22
• Blunders — 2008-01-31
• Goofs — 1999-11-06
• Boo-boos — 1996-12-24