Historical clue formulations

• Stiff — 2026-06-07
• Inflexible — 2025-07-29
• Inflexible — 2025-07-27
• Like hard-liners — 2023-03-14
• Unyielding — 2023-03-12
• Unbending — 2021-09-23
• Stiff — 2021-01-31
• Unbending — 2019-04-02
• Inflexible — 2016-09-18
• Having no flex — 2015-07-12
• Uncompromising — 2011-03-31
• Stiff — 2011-03-21
• Strait-laced — 2009-07-12
• Unyielding — 2008-07-29
• Unforgiving — 2007-09-16
• Infrangible — 2006-02-17
• Unyielding — 2005-09-19
• Unbending — 2005-06-28
• Inflexible — 2005-01-28
• Kind of airship — 1999-01-09
• Unbending — 1998-10-13
• Set — 1997-11-09
• Unbending — 1997-09-23
• Inflexible — 1994-10-05
• Strict — 1994-09-19