2 Components of the environment. Pages 13-28.

H. G. Andrewartha and L. C. Birch. 1954. The Distribution and Abundance of Animals. Chicago: The University of Chicago Press, 782 pages.

Keywords: definition of ecology, analysis of environment: historical, biotic versus abiotic (physical), density-dependent and density-independent, cold-hardiness, Urophora jaceana, Musca and parasitoid Mormoniella, competition, rareness and common species, Megachile, Bombus, the components of environment must be defined in such a way that they can be studied individually, the four components are weather, food, other animals and organisms causing disease, and a place to live