1. International Telecommunication Union. Global mobile cellular subscriptions, total and per 100 inhabitants, 2000-2010. 2011 August 18. http://www.itu.int/ITU-D/ict/statistics/material/excel/2010/Global_mobile_cellular_00-10.xls
2. International Telecommunication Union. Key ICT indicators for developed and developing countries and the world (totals and penetration rates). 2015 February 9. http://www.itu.int/en/ITU-D/Statistics/Documents/statistics/2014/ITU_Key_2005-2014_ICT_data.xls
3. The effects of recall errors and of selection bias in epidemiologic studies of mobile phone use and cancer risk;Vrijheid;J Expo Sci Environ Epidemiol,2006
4. Feasibility of future epidemiological studies on possible health effects of mobile phone base stations;Neubauer;Bioelectromagnetics,2007