Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrenceMike Lockwood, Mathew J. Owens, Luke A. Barnard, Chris J. Scott, Clare E. Watt and Sarah BentleyJ. Space Weather Space Clim., 8 (2018) A12DOI: https://doi.org/10.1051/swsc/2017048
