Positive interactions in communities. Hoare, D.J. et al. The social organization of free-ranging fish shoals. Waller, D.M. and W.S. Alverson. Marquis, R. J. and Whelan, C. J. 1994.
Insectivorous birds increase growth of white oak through consumption of leaf-chewing insects.
Huston, M.A. 1999. Chapin, F.S. et al. Ecosystem consequences of changing biodiversity. The ecology of the Earth s grazing ecosystems. Schneider, E.D. and J.J. Kay.