1. BCR reference materials (Community Bureau of Reference) (1990). Commission of the European Communities, Directorate General for Science, Research and Development, B-1049 Brussels.
2. Quality assurance: achievements, problems, prospects;Brown,1991
3. Participation in BCR-certifications by the laboratory of Analytical Chemistry, Institute for Nuclear Sciences, University of Gent, Belgium;Cornelis;Fres. J. Anal. Chem.,1990
4. Quality assurance and check sample program in the food industry;Elkins,1985
5. BCR information: The certification of the contents (mass fractions) of calcium, potassium, iron, phosphorus and nitrogen in a single cell protein (CRM 273);Griepink,1985