1. D. Hess and E. M. Götz, J. PflPhysiol.85, 185 (1977).
2. E.M. Götz, Z. PflPhysiol.98, 465 (1980).
3. E.M. Götz and D. Hess, Z. PflPhysiol.98, 453 (1980).
4. D. Hess, in: Biochemistry and Physiology of S- and N-metabolism, p. 287. Ed. H. Bothe and H. Trebst. Springer, Berlin-Heidelberg-New York 1981.
5. D. Hess, in: Proc. Int. Workshop on Biological Nitrogen Fixation Technology for Tropical Agriculture. CIAT Publication, in press, Cali 1981.