Historical clue formulations

• Sound effect in the comic "B.C." — 2016-05-28
• "B.C." sound effect — 2015-06-12
• "B.C." sound effect — 2014-08-16
• Sound in the comic "B.C." — 2013-11-23
• Sound from the anteater in "B.C." — 2010-06-18
• Recurring sound effect in the comic "B.C." — 1998-05-13