1. Allee, W. C., A. E. Emerson, O. Park, T. Park &K. P. Schmidt (1949). Principles of Animal Ecology. W. B. Saunders, Philadelphia, xii + 837 pp.
2. Brown, J. L. (1964). The evolution of diversity in avian territorial systems. - Wilson Bull., 76, 160–169.
3. Gibb, J. (1961). Bird populations, pp. 413–446. In:A. J. Marshall (ed.), Biology and Comparative Physiology of Birds. II. Academic Press, New York.
4. Howard, F. (1920). Territory in Bird Life. Atheneum, London, 239 pp.
5. Huxley, J. S. (1934). A natural experiment on the territorial instinct. - Brit. Birds, 27, 270–277.