Gorle, P., & Long, J. (1973). Essentials of product planning. McGraw-Hill.
Čikaški stil citiranjaGorle, Peter, i James Long. Essentials of Product Planning. London: McGraw-Hill, 1973.
MLA način citiranjaGorle, Peter, i James Long. Essentials of Product Planning. McGraw-Hill, 1973.
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