Long-term efficacy of radon spa therapy in rheumatoid arthritis–a randomized, sham-controlled study and follow-up

A. Franke, L. Reiner, H. G. Pratzel, T. Franke, K. L. Resch
Rheumatology, Volume 39, Issue 8, August 2000, Pages 894–902

https://academic.oup.com/rheumatology/article/39/8/894/1784172