1. Microbial co-operation in the rhizosphere
2. Kloepper, J. W., Plant growth–promoting rhizobacteria (other systems). In: Okon Y (Ed.), Azospirillum/plant associations, CRC Press, Boca Raton 1994, pp. 111-118.
3. Proposal for the division of plant growth-promoting rhizobacteria into two classifications: biocontrol-PGPB (plant growth-promoting bacteria) and PGPB
4. The enhancement of plant growth by free-living bacteria
5. Arshad, M., Frankenberger, W. T. Jr.: Microbial production of plant growth regulators, in: Blaine, F., Metting, Jr. (Eds.), Soil microbial ecology. Marcel and Dekker, New York 1993, pp. 307-347.