Goldmann, H. M. (1971). How To Win Customers Heinz M. Goldmann. Pan Book.
Lua i Stíl Chicago (17ú heag.)Goldmann, Heinz M. How To Win Customers Heinz M. Goldmann. Pan Book, 1971.
Lua MLA (8ú heag.)Goldmann, Heinz M. How To Win Customers Heinz M. Goldmann. Pan Book, 1971.
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