Related Clues:

• 'This is a library!'
• Library admonition
• Finger-on-lips sound
• 'Keep it down!'
• Admonition to a cell phone user in a theater
• "Stop talking!"
• 'Silence!'
• Request for quiet
• Teacher's admonition
• Reaction to a library volume?
• Library admonishment
• Theater or library admonishment
• "Zip it!"
• 'Stifle!'
• It may precede 'Don't let anyone hear!'