APA (7th ed.) Citation

British Standards Institution. (1981). Universal decimal classification (2nd English full ed.). British Standards Institution.

Chicago Style (17th ed.) Citation

British Standards Institution. Universal Decimal Classification. 2nd English full ed. London: British Standards Institution, 1981.

MLA (8th ed.) Citation

British Standards Institution. Universal Decimal Classification. 2nd English full ed. British Standards Institution, 1981.