Historical clue formulations

• "I can't think with all this racket!" — 2024-05-29
• "Shh!" — 2023-03-07
• Lull — 2019-10-05
• Need to sleep, maybe — 2017-11-04
• Classroom command — 2017-03-18
• Library sign — 2009-02-18
• "Shhh!" — 2006-10-23
• Angry teacher's cry — 2005-07-03
• "Zip it!" — 2004-03-24
• Pacify — 2003-10-18
• Library sign — 2003-07-11
• "Shush!" — 2002-04-30
• Zipped, so to speak — 2001-03-01
• Hospital caution — 1999-03-21