1. American Society for Testing Materials: ASTM Methods for Chemical Analysis of Metals 1960, p. 134, 136.
2. British Standard 1121; part 25; 1956 (see also ref. 8).
3. Claassen, A., and J. Corbey: Rec. Trav. chim. Pays-Bas 67, 5 (1948).
4. Dutch Standard N 1033 V 1, 1954.
5. Handbuch für das Eisenhüttenlaboratorium, Bd. 4, Schiedsverfahren, S. 116. Düsseldorf 1955.