Graw, L. H. (1994). Service purchasing: What every buyer should know LeRoy H. Graw, Deidre M. Maples. Van Nostrand Reinhold.
Lua i Stíl Chicago (17ú heag.)Graw, LeRoy H. Service Purchasing: What Every Buyer Should Know LeRoy H. Graw, Deidre M. Maples. Van Nostrand Reinhold, 1994.
Lua MLA (8ú heag.)Graw, LeRoy H. Service Purchasing: What Every Buyer Should Know LeRoy H. Graw, Deidre M. Maples. Van Nostrand Reinhold, 1994.
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