APA (7th ed.) Citation

Frøystein, I., Frøystein, I., & Johnsen, M. G. A critical review and presentation of the complete, historic series of <i>K</i> indices as determined at Norwegian magnetic observatories since 1939. Copernicus Publications.

Chicago Style (17th ed.) Citation

Frøystein, I., I. Frøystein, and M. G. Johnsen. A Critical Review and Presentation of the Complete, Historic Series of <i>K</i> Indices as Determined at Norwegian Magnetic Observatories Since 1939. Copernicus Publications.

MLA (9th ed.) Citation

Frøystein, I., et al. A Critical Review and Presentation of the Complete, Historic Series of <i>K</i> Indices as Determined at Norwegian Magnetic Observatories Since 1939. Copernicus Publications.