Historical clue formulations

• One-named singer born Christa Päffgen — 2016-04-14
• One-named singer who was a muse for Andy Warhol — 2015-10-23
• One-named singer/actress associated with Warhol — 2012-03-11
• One-named singer for the Velvet Underground — 2012-01-08
• One-named singer with the 1960s Velvet Underground — 2007-10-13
• Unicorn in a 1998 movie — 2007-06-19
• One-named singer for the 1960s Velvet Underground — 2007-06-05
• One-named singer/model filmed by Andy Warhol — 2001-07-23