APA (7th ed.) Citation

Willoughby, T. C. (1991). External quality-assurance results for the National Atmospheric Deposition Program/National Trends Network during 1989. U.S. Geological Survey.

Chicago Style (17th ed.) Citation

Willoughby, Timothy C. External Quality-assurance Results for the National Atmospheric Deposition Program/National Trends Network During 1989. Denver, Colorado: U.S. Geological Survey, 1991.

MLA (9th ed.) Citation

Willoughby, Timothy C. External Quality-assurance Results for the National Atmospheric Deposition Program/National Trends Network During 1989. U.S. Geological Survey, 1991.