Historical clue formulations

• Have things in common — 2021-05-23
• What a Venn diagram shows — 2020-05-24
• Center of a Venn diagram — 2019-05-10
• What circles in a Venn diagram do — 2012-11-21
• Have in common with — 2003-08-22
• Shared part — 2001-06-09
• Imbricate — 1998-02-27
• Partly coincide — 1997-03-02
• Waste cause — 1994-04-24