Historical clue formulations

• Bob who sang "One love, one heart / Let's get together and feel all right" — 2021-09-27
• Dreaded musician of the 1960s-'70s — 2020-02-16
• Jacob whose ghost appears to Scrooge — 2009-10-27
• Ghost of literature — 2006-09-22
• Fictional ghost — 1997-07-27
• "A Christmas Carol" specter — 1994-06-22
• Bob of reggae — 1994-05-20