Anomalies in the variations of the radon concentration related to geodynamical processes in the volcano Popocatepetl, Mexico - Kotsarenko, Anatoliy; Grimalsky, V.; Koshevaya, S.; Yutsis, Vsevolod; Pérez Enríquez, R.; López Cruz Abeyro, José Antonio; Villegas Cerón, R. A.; Valdés Gonzáles, Carlos (European Geophysical Society, 2009)