1. Breed, R. S., E. G. D. Murray, and A. P. Hitchens: Bergey's Manual of Determinative Bacteriology; 6 th ed. Baltimore, 1948.
2. Fry, B. A., and J. L. Peel (edit.): Autotrophic Micro-organisms. 4 th Symposium of the Society for General Microbiology. Cambridge, 1954.
3. Lees, H.: Biochemistry of Autotrophic Bacteria. London, 1955.
4. Waksman, S. A., and H. A. Lechevalier: Guide to the Classification and Identification of the Actinomycetes and their Antibiotics. New York, 1954.