@Article{npg-20-19-2013,
AUTHOR = {Vasyliūnas, V. M.},
TITLE = {Time scale of the largest imaginable magnetic storm},
JOURNAL = {Nonlinear Processes in Geophysics},
VOLUME = {20},
YEAR = {2013},
NUMBER = {1},
PAGES = {19--23},
URL = {https://npg.copernicus.org/articles/20/19/2013/},
DOI = {10.5194/npg-20-19-2013}
}

@Article{npg-19-667-2012,
AUTHOR = {De Michelis, P. and Consolini, G. and Tozzi, R.},
TITLE = {On the multi-scale nature of large geomagnetic storms: an empirical mode decomposition analysis},
JOURNAL = {Nonlinear Processes in Geophysics},
VOLUME = {19},
YEAR = {2012},
NUMBER = {6},
PAGES = {667--673},
URL = {https://npg.copernicus.org/articles/19/667/2012/},
DOI = {10.5194/npg-19-667-2012}
}