FREUD, J. E. (1977). Elementary Businisess Statistics The Modern Approach John E. Freud Dan Frank J. Williams. Prentice-Hall International.
Lua i Stíl Chicago (17ú heag.)FREUD, John E. Elementary Businisess Statistics The Modern Approach John E. Freud Dan Frank J. Williams. Prentice-Hall International, 1977.
Lua MLA (8ú heag.)FREUD, John E. Elementary Businisess Statistics The Modern Approach John E. Freud Dan Frank J. Williams. Prentice-Hall International, 1977.
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