Historical clue formulations

• One side of the coin — 2022-09-11
• "Heads," to a numismatist — 2013-04-17
• Heads — 2010-08-08
• "Heads" side of a coin — 2010-06-22
• Lincoln's side of the penny — 1999-05-26
• Coin side — 1997-11-25