1. The release of organic substances by cereal roots into the soil;Barber;New Phytol.,1976
2. Plant growth substances produced by microorganisms of soil and rhizosphere;Brown;J. appl. Bact.,1972
3. Nitrogen-fixing bacteria in the rhizosphere;Döbereiner,1974
4. Nitrogen fixation in the rhizosphere of tropical grasses;Döbereiner,1975
5. Root exudates in relation to associative nitrogen fixation in grasses;Gaskins;Agron. Abstr. (U.S.),1976