Cita APA (7a ed.)

Friis-Christensen, E., & Wilhjelm, J. (1974). Polar Cap geomagnetic activity chart: Part B, Southern Polar Cap, January-June 1968. Det Danske Meteorologiske Institut.

Cita Chicago Style (17a ed.)

Friis-Christensen, Eigil, y J. Wilhjelm. Polar Cap Geomagnetic Activity Chart: Part B, Southern Polar Cap, January-June 1968. Kobenhavn: Det Danske Meteorologiske Institut, 1974.

Cita MLA (9a ed.)

Friis-Christensen, Eigil, y J. Wilhjelm. Polar Cap Geomagnetic Activity Chart: Part B, Southern Polar Cap, January-June 1968. Det Danske Meteorologiske Institut, 1974.