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, 
KW  - Teorema das quatro cores
ER  -