TY  - BOOK
AU  - Wilson,Robin
TI  - Four colors suffice: how the map problem was solved 
SN  - 9780691158228
U1  - 511.56 
PY  - 2014///
CY  - United Kingdom
PB  - Princeton University Press
KW  - Four
KW  - color problem
KW  - History
KW  - Mathematical recreations
KW  - Proof theory
ER  -