Cochran, W. G. (2009). Sampling Techniques (3rd edn.). Wiley Eastern.
Lua i Stíl Chicago (17ú heag.)Cochran, William G. Sampling Techniques. 3rd edn. New Dehli: Wiley Eastern, 2009.
Lua MLA (9ú heag.)Cochran, William G. Sampling Techniques. 3rd edn. Wiley Eastern, 2009.
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