MeSH definition : A country located from the Baltic and Black seas to the Pacific Ocean and, for a time
including 15 Soviet Socialist Republics. The capital was Moscow.;
MeSH synonym : soviet union; union of soviet socialist republics;
MeSH annotation : GEN; each former Soviet republic is available as a heading; MOSCOW is also available;
note spelling: no periods; each former Soviet republic is available as a heading; MOSCOW is also available;
Wikipedia link : https://en.wikipedia.org/wiki/Soviet Union;