1. IUPAC Interlaboratory trial on the determination of total selenium in lyophilized human blood serum;Ihnat;J. Pure and Appl. Chem.,1985
2. International Atomic Energy Agency Analytical Control Services Programme, Intercomparison Runs, Certified Reference Materials, Reference Materials 1985-1986, Vienna
3. Interlaboratory comparison of selenium levels in human serum;Kumpulainen;Kern Kemi,1981
4. National Bureau of Standards Certificate of Analysis Standard Reference Material 1571 Orchard Leaves, Washington DC 1977; Certificate of Analysis Standard Reference Material 1577 Bovine Liver, Washington DC 1972; Certificate of Analysis Standard Reference Material 1567 Wheat Flour, Washington DC 1978; Certificate of Analysis Standard Reference Material 1568 Rice Flour, Washington DC 1978