Historical clue formulations

• Blood-typing letters — 2021-11-28
• Blood-typing system — 2021-09-21
• Blood classification system — 2021-07-06
• Blood-typing letters — 2021-04-27
• Blood grouping system — 2021-01-25
• ___ group (hospital classification) — 2020-03-12
• Kind of system in a hospital — 2019-11-16
• Blood type system — 2019-08-18
• Blood-typing letters — 2019-06-09
• System used in hematology — 2019-05-30
• Blood-typing letters — 2019-04-07
• Blood letters — 2017-11-30
• Classification system used in some banks — 2016-12-31
• Blood-typing letters — 2016-08-02
• Blood letters — 2016-03-11
• Blood type system — 2015-08-30
• Blood-typing system — 2015-07-29
• Blood type system — 2014-11-09
• Blood classification system — 2013-12-23
• Red Cross letters — 2013-11-21
• Blood-typing system — 2013-07-05
• Type letters — 2013-01-24
• Blood-typing system — 2012-12-12
• ___ blood-typing — 2012-03-11
• Blood-typing syst. — 2011-11-25
• Blood-typing system — 2011-08-07
• Blood-typing letters — 2011-06-01
• Blood type letters — 2011-05-18
• Blood-typing syst. — 2010-09-29
• Typing letters? — 2009-06-06
• Blood-typing system — 2008-05-21
• Blood-typing letters — 2008-05-18
• Blood type letters — 2007-08-23
• Blood-typing letters — 2007-04-10
• Blood type syst. — 2006-10-18
• Typing letters? — 2006-10-07
• Blood-typing system — 2006-02-21
• Typing system — 2005-12-31
• Blood-typing letters — 2005-12-12
• Blood-typing system — 2005-12-06
• Blood classification — 2005-11-27
• Blood typing system — 2005-11-23
• Blood-type letters — 2005-10-06
• Blood letters — 2004-09-17
• Blood-typing letters — 2004-03-09
• Blood classification system — 2004-01-11
• Blood system — 2003-07-06
• Blood letters — 2003-06-29
• Blood-typing system — 2002-02-13
• ___ system — 2000-07-29