BIBLIOGRAFÍA

1. Barišic, S. et. all. ``Spatial distribution of $\ ^{40}$K, $\ ^{228}$Ra, $\ ^{226}$Ra, $\ ^{238}$U and $\ ^{137}$Cs in surface soil layer observed at small areas'' Uranium exploration data and techniques applied to the preparation of radioelement maps. Proceedings of a technical committee meeting. Vienna: IAEA, 1997. p.p. 135-152.
2. Bevington, Phillip and Keith Robinson. Data reduction and error analysis for the physical sciences. 2nd ed. U.S.A.: McGraw Hill, 1992. 328pp.
3. Evans, Robley D. The Atomic Nucleus U.S.A.: McGraw Hill, 1958. 972pp.
4. Farouk, M. ``Monitoring radioactive contamination in food, water sediments and other environmental samples in Egypt, final report for the period 01/10/1992-31/06/1996'' International Atomic Energy Agency Report No. IAEA-R-7129-F. 1996.
5. Finck, R.R. et. all. ``In situ measurements of environmental gamma radiation by the use of Ge(Li)-spectrometer'' Nuclear Instruments and Methods (Amsterdam)(135):559.1976.
6. Cuadernos técnicos del medio ambiente (Proyecto LIFE) España: Fundación San Valero, 1999. 140pp.
7. Gehrke, R.J. et. all. ``Precise relative $\gamma$-ray intensities for calibration of Ge semiconductor detectors'' Nuclear Instruments and Methods. (Amsterdam)(147):405.1977
8. Heyde, K. Basic ideas and concepts in nuclear physics (Fundamental and applied nuclear physics series) U.K.: Institute of physics publishing. 1994. 424pp
9. Knoll, Glenn. Radiation detection an measurement. 2nd ed. U.S.A.: John Wiley & Sons. 1989. 754pp.
10. Leader, C. et. all. Table of isotopes 7th ed. U.S.A.: John Wiley & Sons. 1978. 1523.
11. McNelles, L.A. and J.L. Campbell ``Absolute efficiency calibration of coaxial Ge(Li) detectors for the energy range 160-1330 keV'' Nuclear Instruments and Methods. (Amsterdam)(109):241.1973
12. Mohamed, Yousif. A study for natural radioactivity levels in some soil samples using gamma spectrometry. Thesis (M.Sc.). Sudan, university of Khartoum. 1991. 81 pp.
13. Mowatt, R.S. ``A semi-empirical efficiency curve for a Ge(Li) detector in the energy range 50 to 1400 keV'' Nuclear Instruments and Methods. (Amsterdam)(70):237.1969
14. Schleich, N. et. all. ``Low-level gamma spectrometry of forest an moor soil from exposed mountain regions in Saxony (Erzgebirge)'' Methods an applications of low-level radioactivity measurements. Proceedings. Dresden: Fietz,-J. 1997. p.p. 123-126.
15. Zobel, V. et. all. ``$\ ^{226}$Ra as calibration standar for Ge(Li) spectrometers'' Nuclear Instruments and Methods. (Amsterdam)(141):329.1977