1. A. R. Flegal, D. R. Smith,Environ. Res. 1992,58, 125.
2. D. Becker, R. Christensen, L. Currie, B. Diamondstone, K. Eberhardt, T. Gills, H. Hertz, G. Klouda, J. Moody, R. Parris, R. Schaffer, E. Steel, J. Taylor, R. Watters, R. Zeisler,NIST Special Publication 829, National Institute of Standards and Technology, 1992.
3. WELAC/EURACHEM,Accreditation for Chemical Laboratories: Guidance on Interpretation of the EN 45000 Series of Standards and ISO/IEC Guide 25, Guidance document WGD2/No. 1, 1993.
4. ISO/REMCON 319,Traceability and Calibration in Analytical Chemistry and Material Testing: Principles and Applications to Real Life, in Connection with ISO 9000, EN 45000 and ISO Guide 25, June 1994.
5. L. Aarons, S. Toon, M. Rowland,J. Pharm. Meth. 1987,17, 337.