Joint perturbation of geoacoustic, emanation, and atmospheric electric fields at the boundary of the earth’s crust and the atmosphere before an earthquakeOleg Rulenko, Yuriy Marapulets, Yuriy Kuzmin and Alexandra SolodchukE3S Web Conf., 11 (2016) 00020DOI: https://doi.org/10.1051/e3sconf/20161100020