Mechanism of unipolar electromagnetic pulses emitted from the hypocenters of impending earthquakesFriedemann T. Freund, Jorge Arturo Heraud, Victor A. Centa and John ScovilleEur. Phys. J. Special Topics, 230 1 (2021) 47-65DOI: https://doi.org/10.1140/epjst/e2020-000244-4