NORTH KLAUS. (1992). ENVIRONMENTAL BUSINESS MANAGEMENT. INTERNATIONAL LABOUR ORGANIZATION.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNORTH KLAUS. ENVIRONMENTAL BUSINESS MANAGEMENT. GENEVA: INTERNATIONAL LABOUR ORGANIZATION, 1992.
एमएलए (9वां संस्करण) प्रशस्ति पत्रNORTH KLAUS. ENVIRONMENTAL BUSINESS MANAGEMENT. INTERNATIONAL LABOUR ORGANIZATION, 1992.
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