1. Allen, M. B.: Photosynthetic nitrogen fixation by blue-green algae. Sci. Monthly83, 100?106 (1956)
2. Anderson, A. J., Spencer, D.: Molybdenum in nitrogen metabolism of legumes and non-legumes. Aust. J. sci. Res.133, 414?430 (1950)
3. Arnon, D. I.: The role of micronutrients in plant nutrition with special reference to photosynthesis and nitrogen assimilation. In: C. A. Lamb, O. G. Bentley, J. M. Beattie, Eds., Trace elements, pp. 1?32. New York: Academic Press 1958
4. Benemann, J. R., McKenna, C. E., Lie, R. F., Taylor, T. G., Kamen, M. D.: The vanadium effect in nitrogen fixation byAzotobacter. Biochim. biophys. Acta (Amst.)264, 25?38 (1972)
5. Bortels, H.: Kurze Notiz �ber die Katalyse der biologischen Stickstoff bindung. Zbl. Bakt., II. Abt.87, 476?477 (1933)