Zikmund, W. G. (2013). Business research methods (9th ed.). South-western cengage learning.
Lua i Stíl Chicago (17ú heag.)Zikmund, William G. Business Research Methods. 9th ed. Andover: South-western cengage learning, 2013.
Lua MLA (8ú heag.)Zikmund, William G. Business Research Methods. 9th ed. South-western cengage learning, 2013.
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