APA (7th ed.) Citation

World Meteorological Organization. (1989). Calculation of monthly and annual 30-year standard normals. World Meteorological Organization.

Chicago Style (17th ed.) Citation

World Meteorological Organization. Calculation of Monthly and Annual 30-year Standard Normals. [Geneva?]: World Meteorological Organization, 1989.

MLA (9th ed.) Citation

World Meteorological Organization. Calculation of Monthly and Annual 30-year Standard Normals. World Meteorological Organization, 1989.