1. Abrantes G T V, Day J M and Dobereiner J 1975 Methods for the study of nitrogenase activity in field grown grasses. Bull. Int. Inf. Biol. 801. 21, 1–7.
2. Balandreau J 1975 Measure de l'activite nitrogenasique des microorganismes fixateurs libres d'azote de la rhizosphere de quelques graminees. Rev. Ecol. Biol. Sol. 12, 273–290.
3. Balandreau J and Dommergues Y 1973 Assaying nitrogenase (C2H2) activity in the field. Bull. Ecol. Comm. NFR (Statens Naturvetensk. Forskningerad), 17, 246–254.
4. Balandreau J, Miller C R, Weinhard P, Ducerf P and Dommergues Y 1977 A modelling approach of acetylene reduction activity of plant-rhizosphere diazotroph systems.In Recent Developments in Nitrogen Fixation. Eds. W Newton, J R Postgate and B Rodrigues. Academic Press, London, pp 523–529.
5. Barber L E, Tjepkema J D, Russell S A and Evans H J 1976 Acetylene reduction (nitrogen fixation) associated with corn inoculated with Spirillum. Appl. Environ. Microbiol. 32, 198–113.