Historical clue formulations

• Probes — 2019-04-14
• Checks out — 2016-02-26
• Checks out — 2015-09-04
• Checks — 2015-03-07
• Checks — 2008-02-24
• See 40-Across — 2006-08-22
• With 21-Down, questions in court — 2006-08-22
• Studies — 1995-02-16