Westerman, M. D. (1993). The business environmental handbook. The Oasis Press/PSI Research.
Lua i Stíl Chicago (17ú heag.)Westerman, Martin D. The Business Environmental Handbook. Grants Pass, Oregon: The Oasis Press/PSI Research, 1993.
Lua MLA (9ú heag.)Westerman, Martin D. The Business Environmental Handbook. The Oasis Press/PSI Research, 1993.
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