(1988). The magnetic field in the United States, 1985: Total intensity chart. U.S. Geological Survey.
Chicago Style (17th ed.) CitationThe Magnetic Field in the United States, 1985: Total Intensity Chart. Denver, CO u.a: U.S. Geological Survey, 1988.
MLA (9th ed.) CitationThe Magnetic Field in the United States, 1985: Total Intensity Chart. U.S. Geological Survey, 1988.
Warning: These citations may not always be 100% accurate.