Columbia subject headings:
Russia--Emigration and immigration--History--Sources.
Russian imprints--Foreign countries--History--Sources.
Russians--Foreign countries--History--Sources.
Soviet Union--Emigration and immigration--History--20th century--Sources.
Harvard subject headings:
Soviet Union--Emigration and immigration--History--Sources.
Princeton subject headings:
Russia--Emigration and immigration--History--Sources.
Russian imprints--Foreign countries--History--Sources.
Russians--Foreign countries--History--Sources.
Soviet Union--Emigration and immigration--History--20th century--Sources.