Radon in spring waters in the south of Catalonia.

Fonollosa E1, Peñalver A1, Borrull F2, Aguilar C
J Environ Radioact. 2016 Jan;151 Pt 1:275-281. doi: 10.1016/j.jenvrad.2015.10.019. Epub 2015 Nov 6

https://www.ncbi.nlm.nih.gov/pubmed/26551586