Historical clue formulations

• 0 — 2026-08-13
• Nada — 2020-04-09
• Nothing, informally — 2018-04-10
• See 1-Across — 2016-09-28
• Bubkes — 2016-08-09
• Nothin' — 2015-01-23
• Nada — 2014-12-17
• It means nothing — 2014-02-28
• Bubkes — 2013-06-15
• Bubkes — 2013-01-29
• Zippo — 2010-05-09
• Nada — 2006-11-05
• Nada — 2000-03-19