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Comparative analysis, measured twice a year
Programs
Articles describing Programs, analytes, units of measurement, preparation of control materials, etc.
Qualitative analysis with test strips. Controls are carried out twice a year
Statistical measurement. Controls are carried out twice a year
Statistical measurement. Controls are carried out twice a year
Statistical measurement. Controls are carried out twice a year
Statistical measurement. Controls are carried out twice a year
Statistical measurement. Controls are carried out twice a year
Statistical measurement. Controls are carried out 12 times a year
Statistical measurement. Controls are carried out twice a year