Graphical Schemes Designed to Display and Study the Long-term Variations of Schumann Resonance. - Jesús Rodríguez-Camacho; Juan Francisco Gómez-Lopera; Alfonso Salinas; Jesús Fornieles-Callejon; Jorge Porti; David Blanco-Navarro; Maria Carmen Carrion Perez; Enrique Navarro-Camba (EUSIPCO, 2019)