Columbia subject headings:
Harvard subject headings:
Portugal--Boundaries--Spain.
Portugal--Commerce--Spain.
Smuggling--Portugal--Beira Baixa.
Spain--Boundaries--Portugal.
Spain--Commerce--Portugal.
Princeton subject headings:
Portugal--Boundaries--Spain.
Portugal--Commerce--Spain.
Smuggling--Portugal--Beira Baixa.
Spain--Boundaries--Portugal.
Spain--Commerce--Portugal.