TY  - BOOK
T1  - The Four-color problem
A1  - Saaty, Thomas L.
LA  - English
PP  - New York
PB  - Mcgraw-Hill Book
YR  - 1977
UL  - https://ds.mainlib.upd.edu.ph/Record/UP-99796217607717514
OP  - 217
CN  - QA611 S23 1977
SN  - 0070543828
ER  -