Dewey Decimal System
From Tardis Wiki, the free Doctor Who reference
The Dewey Decimal System was a numbering system used in libraries. After two days of working in the Hounslow Library, Donna Noble memorised it. She later used this as proof that she was "good with numbers". (TV: The Doctor's Daughter)
On Folly, the Fifth Doctor organised the prison library according to the Dewey System. (AUDIO: Doing Time)
