Historical clue formulations

• One-of-a-kind — 2025-10-07
• One-of-a-kind — 2023-11-27
• Sui generis — 2020-10-04
• Peerless — 2000-04-02
• More than unusual — 2000-03-21
• Rarer than rare — 1999-08-05
• Unparalleled — 1996-06-16