Historical clue formulations

• Swiss capital, to French speakers — 2017-06-12
• European capital — 2013-12-22
• Capitale européenne — 2013-09-28
• Capital SSW of Basel — 2010-08-25
• City on the Aar — 2008-11-26
• 1960's best-selling author Eric — 2002-08-15
• Swiss capital — 2001-08-13
• "Games People Play" author — 1999-08-14
• Home of the Universal Postal Union — 1999-07-01
• European capital — 1998-08-30
• International copyright center — 1996-12-27
• "Games People Play" author Eric — 1996-05-28
• Copyright treaty city — 1994-09-11
• European capital — 1994-08-11
• Swiss capital — 1993-11-24