What subjects do the call letters cover?
Subclass D History (General).
Subclass DA History of Great Britain.
Subclass DAW History of Central Europe.
Subclass DB History of Austria. Liechtenstein. Hungary. Czechoslovakia.
Subclass DC History of France.
Subclass DD History of Germany.
Subclass DE History of the Greco-Roman world.
Subclass DF History of Greece.
Subclass DG History of Italy.
Subclass DH History of Low Countries. Benelux Countries.
Subclass DJ History of Netherlands (Holland).
Subclass DJK History of Eastern Europe (General).
Subclass DK History of Russia. Soviet Union. Former Soviet Republics.
Subclass DL History of Northern Europe. Scandinavia.
Subclass DP History of Spain.
Subclass DQ History of Switzerland.
Subclass DR History of Balkan Peninsula.
Subclass DS History of Asia.
Subclass DT History of Africa.
Subclass DU History of Oceania (South Seas).
Subclass DX History of Romanies.