APA (7th ed.) Citation

(1970). Universal decimal classification: Key to information. International Federation for Documentation.

Chicago Style (17th ed.) Citation

Universal Decimal Classification: Key to Information. The Hague: International Federation for Documentation, 1970.

MLA (9th ed.) Citation

Universal Decimal Classification: Key to Information. International Federation for Documentation, 1970.

Warning: These citations may not always be 100% accurate.