1. Ministry of Education, Culture, Sports, Science and Technology. Readings of environmental radioactivity level by prefecture (March 2011).
http://radioactivity.nsr.go.jp/ja/list/224/list-201103.html
(The last date of access: 25 March 2014).
2. Ministry of Education, Culture, Sports, Science and Technology. Preparation of Distribution Map of Radiation Doses, etc. (Map of Radioactive Cesium Concentration in Soil) by MEXT (2011).
http://radioactivity.nsr.go.jp/en/contents/5000/4165/24/1750_083014.pdf
(Date of access: 12 March 2014).
3. Ministry of Education, Culture, Sports, Science and Technology. Results of the fourth airborne monitoring survey by MEXT (2011).
http://radioactivity.nsr.go.jp/en/contents/4000/3179/24/1270_1216.pdf
(Date of access: 4 March 2014).
4. Torii, T., Sugita, T., Okada, C., Reed, M. & Blumenthal, D. Enhanced analysis methods to derive the spatial distribution of 131I deposition on the ground by airborne surveys at an early stage after the Fukushima Daiichi Nuclear Power Plant accident. Health Phys. 105, 192–200 (2013).
5. Saito, K. et al. Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides from the Fukushima Daiichi Nuclear Power Plant accident. J. Environ. Radioact. 10.1016/j.jenvrad.2014.02.014 (2014). (in press).