Historical clue formulations

• Vinegar: Prefix — 2009-08-07
• Vinegar: Prefix — 2008-09-28
• Vinegar: Prefix — 2008-04-01
• Prefix with nitrile — 2006-01-01
• Prefix with phenetidin — 2005-12-16
• Vinegar: Prefix — 2002-08-22
• Vinegar: Prefix — 2000-04-03
• Vinegar: Prefix — 1999-09-01
• Vinegar: Prefix — 1999-07-09
• Chemical prefix — 1999-05-02
• Acidic prefix — 1998-11-29
• Vinegar: Prefix — 1997-02-18
• Vinegar: Prefix — 1994-06-14
• Vinegary prefix — 1994-02-19