APA (7th ed.) Citation

Geological Survey (U.S.). (1984). Humboldt, Iowa: 1:100 000-scale planimetric map 30 x 60 minute series (planimetric). The Survey.

Chicago Style (17th ed.) Citation

Geological Survey (U.S.). Humboldt, Iowa: 1:100 000-scale Planimetric Map 30 X 60 Minute Series (planimetric). Reston, Va.: The Survey, 1984.

MLA (9th ed.) Citation

Geological Survey (U.S.). Humboldt, Iowa: 1:100 000-scale Planimetric Map 30 X 60 Minute Series (planimetric). The Survey, 1984.