APA (7th ed.) Citation

Clifford, H. T., & Stephenson, W. (1975). An introduction to numerical classification. Academic Press.

Chicago Style (17th ed.) Citation

Clifford, H. T., and William Stephenson. An Introduction to Numerical Classification. New York [etc.]: Academic Press, 1975.

MLA (9th ed.) Citation

Clifford, H. T., and William Stephenson. An Introduction to Numerical Classification. Academic Press, 1975.