Historical clue formulations

• Inscrutable sorts — 2024-10-04
• Head-scratchers — 2024-04-11
• Great mysteries — 2024-03-29
• Mysteries — 2021-03-03
• Puzzlements — 2017-07-05
• Mysteries — 2013-10-14
• Causes of head-scratching — 2013-05-31
• They're hard to figure out — 2012-04-13
• Riddles — 2009-10-27
• Knots — 2007-02-15
• W.W. II code machines — 2003-12-28
• Riddles — 2002-05-14
• Mysteries — 2001-10-21
• Posers — 2001-04-28
• Mysteries — 1998-12-23
• Riddles — 1997-07-01
• Posers — 1995-05-29