1. Bowe HJ (1979) Environmental chemistry of the elements. Academic Press, San Diego, CA
2. Purves D (1985) Trace elemental contamination of the environment. Elsevier, New York
3. Underwood EJ (1977) Trace elements in human and animal nutrition. Academic Press, New York
4. El-Ghawi UM, Bogdanovic I (1995) Determination of some toxic and essential elements in soils at Tripoli city using ED-XRF analytical method. 3rd Intern. Conf. on the Biogeochemistry of Trace Elements, Paris, France, May 15–19, 1995
5. El-Ghawi UM, Vajda N, Patzay Gy (1999) Determination of some trace elements in natural and fertilized Libyan soils using INAA and ED-XRF. J Radioanal Nucl Chem 241(3):605–610