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2. Selection of metals in the construction of dairy equipment;Hunziker;Proc. World's Dairy Congress,1923
3. Observations on copper and iron contents of milk and other dairy products;Davies;J. of Dairy Res.,1931
4. Determination of copper and iron in dairy products;Williams;J. of Dairy Res.,1931
5. Ritter, W. Der Nachweis von Kupfer in Butter und Butterschmalz dureh die Peroxydase-Reaktion. Schweizerische Milchzeitung. No. 6. 1936.