Historical clue formulations

• "Eureka!" — 2019-11-27
• "Eureka!" — 2018-10-24
• "Here's the solution!" — 2017-06-21
• "Eureka!" — 2015-02-08
• "Aha!" — 2013-01-28
• "Eureka!" — 2006-07-09
• Puzzle solver's exclamation — 1997-11-16