1. Council Directive 90/167/EEC laying down the conditions governing the preparation, placing on the market and use of medicated feeding stuffs in the community.
2. Real Decreto 2257/1994. Aprueba los métodos oficiales de análisis de piensos o alimentos para animales y sus primeras materias. BOE No. 52, 2 March 1995.
3. Determination of Tetracyclines in Animal Feeds in the Presence of Other Drugs by Thin-Layer Chromatography and Microbiological Method
4. AOAC International, Official methods of analysis, Oxytetracycline in Feeds and Antibiotics in Feeds (methods 957.23 B and 968.50), Vol. 1, 16th Edition, 1997.
5. Liquid Chromatographic Determination of Tetracycline Residues in Animal Feeds