Historical clue formulations

• Part of a ream — 2019-10-05
• Paper unit — 2015-09-04
• Paper quantity — 2008-04-01
• Paper purchase — 2004-11-09
• Leaf collection? — 2000-11-02
• Paper quantity — 1999-09-22
• Set of sheets — 1999-01-29
• 24 sheets of paper — 1997-09-02
• Stationery amount — 1996-02-16