1. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life;Darwin,1859
2. The struggle for existence;Gause,1934
3. The niche-relationships of the California thrasher;Grinnell;The Auk,1917
4. The competitive exclusion principle;Hardin;Science,1960
5. Multiple scales and the maintenance of biodiversity;Levin;Ecosystems,2000