Columbia subject headings:
Queens--Russia--Correspondence.
Russia--Kings and rulers--Correspondence.
Harvard subject headings:
Kings and rulers--Correspondence.
Kings and rulers--Russia--Correspondence.
Queens--Russia--Correspondence.
Russia--Kings and rulers--Correspondence.
Princeton subject headings:
Empresses--Russia--Correspondence.
Kings and rulers--Russia--Correspondence.
Russia--Kings and rulers--Correspondence.