Some of the best-known representatives of holism include:

Callicot, J. B. (1989): In Defense of the Land Ethic: Essays in Environmental Philosophy. Albany: SUNY Press. 

Leopold, A. (1949) A Sand County Almanac. And Sketches Here and There. Oxford: Oxford University Press. 

Rolston, H. (1975): Is There an Ecological Ethic? In: Ethics 85, 93–109. 

A good general overview of the various currents in environmental ethics can be found in:

Krebs, A. (ed.): Naturethik. Grundtexte der gegenwärtigen tier- und ökoethischen Diskussion. 8. Ed. Frankfurt a. M.: Suhrkamp. (German)

Krebs, A. (1999): Ethics of Nature. A Map. Berlin/New York: Walter de Gruyter.