Prol Ledesma, R.M., Medina, F., Choporov, D.Y., Frikh K., D.I., Muravitskaya, G.N., Polak, B.G. and Stepanets, M.I. 1982. Preliminary chemical and petrographic results of the march-april "El Chichon" volcanics. Geofisica Internacional. 21, 1 (Jan. 1982), 1–10. DOI:https://doi.org/10.22201/igeof.00167169p.1982.21.1.1073.