National Productivity Corporation & Perbadanan Produktiviti Negara. (1997). Productivity primer. National Productivity Corporation.

National Productivity Corporation and Perbadanan Produktiviti Negara. Productivity Primer. Petaling Jaya: National Productivity Corporation, 1997.

National Productivity Corporation and Perbadanan Produktiviti Negara. Productivity Primer. National Productivity Corporation, 1997.