1. L. N. Filimonov and V. V. Polyakova, Zav. lab.,25, 8 (1959).
2. List of Standard Specimens of Chemical Compositions and Reference Standards for Spectral Analysis [in Russian], MChM USSR, VNIISO, Sverdlovsk (1966).
3. Federal Register NBS,30, No. 74, 2 (1965).
4. Complete List of British Chemical Standards and Spectrographic Standards, No. 386, Bureau of analyzed samples (1956).
5. Spectrographically standardized substances. Mathey standard for quantitative spectrochemical analysis, Johnson, Mathey and Co., Ltd., London (1956).