1. Ger. Offen. 2140674 (1972).
2. Stoffwechselprodukte von Mikroorganismen
3. and Abstracts, Second World Congress on Animal Feeding, Madrid, October 1972, p. 27.
4. and in Topics in Antibiotic Chemistry, edited by Vol. 5, p. 150. Halsted Press, New York (1980).