The Eastern Bloc was the group of socialist states of Central and Eastern Europe, generally the Soviet Union and the countries of the Warsaw Pact.
An encyclopedia or encyclopaedia is a reference work or compendium providing summaries of information from either all branches of knowledge or from a particular field or discipline.
Latvian (latviešu valoda) is a Baltic language spoken in the Baltic region.
Riga (Rīga) is the capital and largest city of Latvia.
Russian (rússkiy yazýk) is an East Slavic language, which is official in Russia, Belarus, Kazakhstan and Kyrgyzstan, as well as being widely spoken throughout Eastern Europe, the Baltic states, the Caucasus and Central Asia.