APA (7th ed.) Citation

World Data Center A for Solid Earth Geophysics & National Geophysical Data Center. (1992). Geomagnetic observatories in operation, 1990. National Geophysical Data Center.

Chicago Style (17th ed.) Citation

World Data Center A for Solid Earth Geophysics and National Geophysical Data Center. Geomagnetic Observatories in Operation, 1990. Boulder, Colo.: National Geophysical Data Center, 1992.

MLA (9th ed.) Citation

World Data Center A for Solid Earth Geophysics and National Geophysical Data Center. Geomagnetic Observatories in Operation, 1990. National Geophysical Data Center, 1992.