APA (7th ed.) Citation

British Institute of International Affairs & Royal Institute of International Affairs. (1920). British yearbook of international law. Royal Institute of International Affairs.

Chicago Style (17th ed.) Citation

British Institute of International Affairs and Royal Institute of International Affairs. British Yearbook of International Law. [London?]: Royal Institute of International Affairs, 1920.

MLA (9th ed.) Citation

British Institute of International Affairs and Royal Institute of International Affairs. British Yearbook of International Law. Royal Institute of International Affairs, 1920.