Historical clue formulations

• Worked sufferingly — 2026-07-16
• Worked — 2024-02-12
• Put in work — 2021-04-10
• Put one's nose to the grindstone — 2016-05-14
• Worked — 2003-09-07
• Labored — 2002-12-26
• Slaved away — 2001-07-03
• Slaved — 1998-07-16