KEITH, L. A. (1975). Introduction To Business Enterprise Lyman A. Keith Dan Carlo E. Gubellini. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)KEITH, Lyman A. Introduction To Business Enterprise Lyman A. Keith Dan Carlo E. Gubellini. McGraw-Hill, 1975.
Lua MLA (8ú heag.)KEITH, Lyman A. Introduction To Business Enterprise Lyman A. Keith Dan Carlo E. Gubellini. McGraw-Hill, 1975.
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