Columbia subject headings:
Baltic Coast--History--Congresses.
Seaside resorts--Baltic Coast--History--Congresses.
Tourism--Baltic Coast--History--Congresses.
Harvard subject headings:
Baltic Sea Region--Social life and customs--19th century--Congresses.
Baltic Sea Region--Social life and customs--20th century--Congresses.
Seaside resorts--Baltic Sea Region--History--19th century--Congresses.
Seaside resorts--Baltic Sea Region--History--20th century--Congresses.
Princeton subject headings:
Baltic Coast--History--Congresses.
Seaside resorts--Baltic Coast--History--Congresses.
Tourism--Baltic Coast--History--Congresses.