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2. E. Haeckel, Generelle Morphologie der Organismen, Berlin 1866, II. Bd., S. 286
3. W. P. Taylor, What is Ecology and what good is it? in Z. Ecology vol. XVII, 1936, S. 335
4. J. W. Bews, Human Ecology, London 1935, S. 1.
5. Amos H. Hawley, Human Ecology: A Theorie of Community structure, New York 1950, S. 3