1. Aldhous, J.R. (1972) in Lowland Forestry and Wildlife Conservation (ed. R.C. Steele ), Monks Wood Experimental Station. Symp. No. 6.
2. Allen, R. (1974) New Scientist, 63, 528–529.
3. Anderson, M. (1979) in Ecology and Design in Amenity Land Management (eds S.E. Wright & G.P. Buckley), Wye College, London.
4. Anderson, M.A. (1980) Landscape Planning, 7, 1–22.
5. Ashby, E. (1979) The Search for an Environmental Ethic, The Tanner Lecture on Human Values, University of Utah.