Historical clue formulations

• Three times daily, in Rx's — 2015-10-25
• Where seawater remains after an ebb — 2013-04-18
• Thrice daily, on an Rx — 2009-11-15
• Prescription abbr. — 2008-12-23
• Three times a day, on an Rx — 2008-08-31
• Rx instruction — 2007-12-15
• Rx instruction — 2005-10-02
• Pharmacist's abbr. — 2003-03-27
• Rx instruction — 2000-09-23
• Thrice daily, in pharm. — 1998-07-12
• Thrice daily, in prescriptions — 1998-04-19
• Prescription abbr. — 1996-12-15
• Thrice a day, on prescriptions: Abbr. — 1994-07-03