Each Branch library is arranged according the the Library of Congress Classification system. Once you know the general area where books on your topic are kept, it can be very effective to browse the shelves. How to read a call number
D History (General)
DA Great Britain
DAW Central Europe
DB Austria - Liechtenstein - Hungary - Czech & Slovakia
DC France - Andorra - Monaco
DD Germany
DE Greco-Roman World
DF Greece
DG Italy - Malta
DH Low Countries - Benelux Countries
DJ Netherlands (Holland)
DJK Eastern Europe (General)
DK Russia. Soviet Union. Former Soviet Republics - Poland
DL Northern Europe. Scandinavia
DP Spain - Portugal
DQ Switzerland
DR Balkan Peninsula
DS Asia
DT Africa
DU Oceania (South Seas)
DX Romanies
E 11-143 America
E 151-904 United States
F 1-975 United States local history
F 1001-1145.2 British America (including Canada)
F 1201-3799 Latin America. Spanish America