1. Koch KH (1990) Kontrolle, Oktober:80
2. Günzler H (ed) (1996) Accreditation and quality assurance in analytical chemistry. Springer, Berlin Heidelberg New York
3. Theuer A (1990) LABO 12/1990:7
4. Kremer K-J (1989) Stahl u. Eisen 109:119
5. DIN 55350 (Part 11) (1987): Concepts in quality and statistics; basic concepts in quality management, quality control and quality assurance