[1] National Council on Radiation Protection. Exposure of the population in the United States and Canada from Natural Background Radiation. NCRP No. 94 (1992).
[2] National Council on Radiation Protection. Ionizing Radiation Exposure of the Population of the United States. NCRP No. 160 (2009).
[3] G. Campos Venuti, S. Colili, A. Grisianti, G. Grisanti, G. Monteleone, S. Risica, G. Gobbi, M.P. Leogrande, A. Antonini, and R. Borio. Indoor exposure in a region of Central Italy. Radiat. Prot. Dos. 7(1984) 271–274.
[4] K. Saito, T. Sakamoto, M. Nagaoka, M. Tsusumi and S. Moriuchi. Measurement of gamma dose rates in dwellings in the Tokyo metropolitan area. Radiat. Prot. Dosim. 69(1) (1997) 61–67.
[5] K.N. Yu, Z.J. Guan, M.J. Stokes and E.C.M. Young. The assessment of the natural radiation dose committed to the Hong Kong people. J. Environ. Radioact. 17(1992)31–48.
[6] United Nations. Sources and effects of ionizing radiation. United Nations Scientific Committee on the Effects of Atomic Radiation. (UNSCEAR), United Nations Publications (1993).
[7] United Nations. Exposures from natural radiation sources. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), 2000 Report to the General Assembly, V. 1, Annex B. UN. (2000).
[8] M. Sohrabi. The state-of-the-art on worldwide studies in some environments with elevated naturally occurring radioactive materials (NORM). Appl. Radiat. Isotopes 49(1998) 169–188.
[9] J. Hendry, S.L. Simon, A. Wojcik, M. Sohrabi, W. Burkart, E. Cardis, D. Laurier, M. Tirmarche and I. Hayata. Human exposure to high natural background radiation: what can it teach us about radiation risks? J. Radio. Prot. 29(2009) A29–A42.
[10] N. Rostampour, T. Almasi, M. Rostampour, M. Mohammadi, KG. Sani, HR. Khosravi. An investigation of gamma background radiation in Hamadan province, Iran. Radiat Prot Dosimetry 43(2012) 438.
[11] MR. Abdolrahimi. Measurement of annually doses from environmental gamma radiation in Khorasan Provinc. M.S.c. thesis,Mashhad University of Medical Scienses, Mashhad (2002).
[12] T.S.M.T. Bahreyni and M. yarahmadi. "Comparison of Indoor and outdoor dose rates from Environmental Gamma radiation in Kurdistan Province. Journal of Kerman University of Medical Sciences 16 (2009) 255-262.
[13] M. Gholami, S. Mirzaei and A. Jomehzadeh. Gamma background radiation measurement in Lorestan province, Iran. Iranian Journal of Radiation Research 9(2011) 89-93.
[14] F. Saghatchi, M. Salouti and A. Eslami. Assessment of annual effective dose due to natural gamma radiation in Zanjan (Iran). Radiat Prot Dosimetry 132(2008) 346.
[15] M. Sohrabi, N. Alirezazadeh and H. Tajik Ahmadi. A survey of 222 Rn concentrations in domestic water sup- plies in Iran. Health Phys. 75(1998) 417–421.
[16] M. Sohrabi, M.M. Beitollahi, S. Hafezi and M. Assefi. Public exposure from 226 Ra in drinking water supplies of Iran. Health Phys. 77(2) (1999) 150–154.
[17] M. Sohrabi and A.R. Solaymanian. Indoor radon level measurements in some regions of Iran. Nucl. Tracks Radiat.Meas. 15, Nos. 1–4(1988) 613–616.
[18] M.R. Kardan, N. Fathabadi, A. Attarilar, M.T. Esmaeili, M. Karimi, A. Najafi and S.S. Hosseini. A national survey of natural radionuclides in soils and terrestrial radiation exposure in Iran. Journal of Environmental Radioactivity (2017)168-176.
[19] M. Sohrabi and A.R. Esmaili. New public dose assessment of elevated natural radiation areas of Ramsar (Iran) for epidemiological studies. Int. Cong. Ser.1225 (2002) 15-24.
[20] M. Ghiassi-nejad, S.M.J. Mortazavi, J.R. Cameron, A. Niroomand-rad and P.A. Karam. Very high background radiation areas of Ramsar, Iran: preliminary biological studies. Health Phys. 82 (1) (2002) 87-93.
[21] M. Ghiassi - Nejad, M.M. Beitolahi, N. Fallahian and M. Saghirzade. New finding in very high natural radon area at Ramsar, Iran. International Congress Series 1276 (2005).
[22] E. Bavarnegin , N. Fathabadi, M. Vahabi Moghaddama, M. Vasheghani Farahani, M. Moradi and A. Babakhni "Radon exhalation rate and natural radionuclide content in building materials of high background areas of Ramsar, Iran. Journal of Environmental Radioactivity 117(2013) 36-40.