Historical clue formulations

• Book page size — 2019-08-03
• Book size — 2015-02-19
• Smallish printing format — 2012-05-12
• Book size — 2010-07-10
• Book size — 2007-08-06
• Book specification — 2004-09-09
• Book size — 2003-11-27
• 6 x 9-inch book size — 2000-08-25