Historical clue formulations

• Soviet workers' group — 2019-06-29
• Soviet co-op — 2016-06-11
• Old Russian co-op — 2010-12-02
• Soviet co-op — 2010-03-14
• Soviet cooperative — 2006-07-16
• Russian cooperative — 2003-06-07
• Soviet co-op — 1999-10-03
• Soviet cooperative — 1996-07-13
• Soviet co-op — 1995-08-30
• Soviet cooperative — 1994-12-28
• Russian co-op — 1994-12-21
• Soviet workers' cooperative — 1994-09-01