Historical clue formulations

• Like oak leaves and brains — 2014-09-08
• Like brains — 2011-03-09
• Like ears — 2006-05-28
• Like sycamore leaves — 2002-02-17
• Like oak leaves — 2000-05-21
• Like oak leaves — 1997-04-02
• Like oak leaves — 1996-03-12