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2. Anonymous, 2002. The Danish Advisory Centre. Principles of Danish Cattle Breeding. Danish Milk and Livestock Federation. 5th edition, 50 pp. http://www.lr.dk/kvaeg/diverse/principles.pdf
3. Swiss experiences on practical cattle breeding strategies for organic dairy herds;Bapst,2001
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5. Wende in der Nutztierzucht–Ökologische Gründe;Boehncke;Tierärztl. Umschau,1998