TY  - BOOK
AU  - Saaty, Thomas L.
TI  - The four-color problem: assaults and conquest 
SN  - 0070543828 :
U1  - 511.5 
PY  - 1977///
CY  - New York
PB  - McGraw-Hill International Book
KW  - Four-color problem
N1  - Includes index
ER  -