Columbia subject headings:
Denmark--Foreign relations--Russia.
Russia--Foreign relations--1689-1801.
Russia--Foreign relations--Denmark.
Harvard subject headings:
Denmark--Foreign relations--Soviet Union.
Russia--Foreign relations--1689-1801.
Schloss Gottorp.
Soviet Union--Foreign relations--Denmark.
Princeton subject headings:
Denmark--Foreign relations--Russia.
Russia--Foreign relations--1689-1801.
Russia--Foreign relations--Denmark.