Gerstenberg, C. W. 1. (1922). Principles of business (4th ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Gerstenberg, Charles William 1882. Principles of Business. 4th ed. New York: Prentice-Hall, 1922.
Lua MLA (9ú heag.)Gerstenberg, Charles William 1882. Principles of Business. 4th ed. Prentice-Hall, 1922.
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