Historical clue formulations

• Originator of 61-Across — 2021-01-04
• Flash setting — 2020-09-12
• Distributor of Penguin classics? — 2018-07-28
• Flash source — 2017-01-06
• *Green Lantern company — 2012-04-25
• "Captain Marvel" publisher ... and a hint to 17-, 25-, 37- and 50-Across — 2011-08-02
• Company associated with Batman — 2003-06-27