Columbia subject headings:
Willers, Gerhard, 1846-1906--Correspondence.
Harvard subject headings:
Germans--Russia--Biography.
Germans--Russia--Correspondence.
Oldenburg (Grafschaft)--Relations--Russia.
Physicians--Germany--Oldenburg--Biography.
Physicians--Russia--Biography.
Physicians--Russia--Correspondence.
Russia--History--1801-1917--Sources.
Russia--Relations--Germany--Oldenburg (Grafschaft)
Willers, Gerhard, 1846-1906--Correspondence.
Willers, Gerhard, 1846-1906--Family.
Willers, Gerhard, 1846-1906.
Princeton subject headings: