Historical clue formulations

• Frequent quotation attribution: Abbr. — 2021-08-03
• Common English lit subj. — 2015-03-21
• Source of the phrases "cakes and ale" and "milk of human kindness": Abbr. — 2014-05-10
• Most-quoted author in the O.E.D.: Abbr. — 2011-11-20
• Big section of Bartlett's: Abbr. — 2010-08-26
• Common quotation attribution: Abbr. — 1997-01-10