1. Babchuck, A., and N., Booth: 1969, ?Voluntary association membership: a longitudinal analysis?, American Sociological Review 34, pp. 31?45.
2. ERS-USDA, ERS-605;C. L. Beale,1975
3. Blau, P. M. and O. D., Duncan: 1967, The American Occupational Structure (Wiley, New York).
4. Bookchin, M.: 1974, The Limits of the City (Harper Colophon, New York).
5. DeJong, G. F. and R. R., Sell: 1977, ?Population redistribution, migration, and residential preferences?, Annals 429, pp. 130?144.