Historical clue formulations

• Last month — 2020-04-25
• Last month — 2013-06-15
• Last, to Luigi — 2010-04-03
• Last, in León — 2009-05-17
• In the previous month — 2007-01-17
• Last month — 2006-12-31
• Of last month — 2005-11-20
• Last month — 1997-09-20