1. Colgan P, Exposure to radon in Spain a general review. Instituto de Medio Ambiente. CIEMAT/IMA/52F11. Madrid. 1995
2. Green B, Lomas P, Bradley E, Wrixon A. Gamma radiation levels outdoors in Great Britain. NRPB-191. Chilton. 1989
3. IAEA. International Agency for Atomic Energy. Use of uranium airborne survey data in the preparation of radiometric map of Spain. Vienna: IAEA-TECDOC-827. 1993
4. ICRP. International Commission on Radiological Protection. Lung cancer risk from indoor exposures to radon daughters. Oxford: Pergamon Press; ICRP Publication 50: 1987
5. ICRP. International Commission on Radiological Protection. Protection against radon-222 at home and at work. Oxford: Pergamon Press; ICRP Publication 65: 1994