Best, E. P. H., & Haeck, J. (1983). Ecological indicators for the assessment of the quality of air, water, soil, and ecosystems: Papers presented at a symposium held in Utrecht, October 1982. Dordrecht: Reidel.

Best, E. P. H., and J. Haeck. Ecological Indicators for the Assessment of the Quality of Air, Water, Soil, and Ecosystems: Papers Presented At a Symposium Held in Utrecht, October 1982. Dordrecht: Reidel, 1983.

Best, E. P. H., and J. Haeck. Ecological Indicators for the Assessment of the Quality of Air, Water, Soil, and Ecosystems: Papers Presented At a Symposium Held in Utrecht, October 1982. Dordrecht: Reidel, 1983.