Historical clue formulations

• "It is a riddle, wrapped in a mystery, inside an enigma; but perhaps there is ___": Churchill — 2018-11-18
• Answer to the riddle "What force or strength cannot get through / I, with gentle touch, can do" — 2017-06-20
• Solution to the classic riddle "What force or strength cannot get through, / I, with gentle touch, can do" — 2014-07-23
• "The House Without ___" (first Charlie Chan mystery) — 2009-07-15
• Caps Lock neighbor, on a computer — 1997-03-12