1. Abram, D. (1988). Merleau-Ponty and the voice of the earth. Environmental Ethics, 10, 101–120.
2. Abram, D. (1997). The spell of the sensuous. Perception and language in a more-than-human world. New York: Vintage Books.
3. Brier, S. (2001). Cybersemiotics and Umweltlehre. Semiotica, 134(1/4), 779–814.
4. Brown, C. S. & Toadvine, T. (Eds.) (2003). Eco-phenomenology: back to the earth itself. Albany: State University of New York Press.
5. Deely, J. (2001). Umwelt. Semiotica, 134(1/4), 125–135.