De Lauretis, M., Francia, P., Piancatelli, A., Vellante, M., & Villante, U. (2009). Low and mid-frequency pulsations in the polar cap: polarization pattern and MLT dependence of the spectral power during the descending phase of the solar cycle. Annals of Geophysics, 52(1), 27–34. https://doi.org/10.4401/ag-4570