1. Feed Additive Compendium, Feedstuffs, Miller Pub. Co., Minneapolis, Minn., published yearly with supplements.
2. Manual of Microscopic Analysis of Feeding Stuffs, American Association of Feed Microscopists, obtainable from G.M. Barnhart, Missouri Dept. of Agriculture, Jefferson City, Mo., U.S.A.
3. Chromatographic separation of Rauwolfia serpentina and opium alkaloids on thin layers of alumina