Columbia subject headings:
Conference on Freedom of Communications and Transit (1st : 1921 : Barcelona)
Inland navigation.
International law.
International rivers.
Harvard subject headings:
General Conference on Freedom of Communications and Transit (1st : 1921 : Barcelona, Spain)
Inland navigation--Law and legislation.
International rivers.
Princeton subject headings:
Conference on Freedom of Communications and Transit (1st : 1921 : Barcelona, Spain)
Inland navigation.
International law.
International rivers.