Segovia, N., P. Peña, C. Valdés, M. A. Armienta, B. Lopez, G. Cisniega, and M. Mena. 2005. “Radon, Water Chemistry and Pollution Check by Volatile Organic Compounds in Springs Around Popocatepetl Volcano, Mexico”. Annals of Geophysics 48 (1). https://doi.org/10.4401/ag-3182.