Historical clue formulations

• Frankie of the Four Seasons — 2022-06-08
• Role in the 2005 hit musical "Jersey Boys" — 2020-07-26
• Frankie of the Four Seasons — 2015-01-05
• Frankie of the Four Seasons — 2013-04-23
• "Grease" singer — 2012-10-07
• "Swearin' to God" singer, 1975 — 2012-03-09
• Frankie of the Four Seasons — 2008-09-08
• One of the Four Seasons — 2008-08-03
• "Rag Doll" singer, 1964 — 2007-11-08
• 1960's-70's vocalist known for his falsetto — 2006-08-12
• Frankie of the Four Seasons — 2005-08-29
• "Grease" singer — 2000-11-26
• Singer with a falsetto — 1998-04-05
• "Grease" singer — 1995-08-20