Freund, J. E., & Williams, F. J. (1972). Elementary business statistics: The modern approach (2nd ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Freund, John E., agus Frank Jefferson Williams. Elementary Business Statistics: The Modern Approach. 2nd ed. Englewood Cliffs, N.J: Prentice-Hall, 1972.
Lua MLA (9ú heag.)Freund, John E., agus Frank Jefferson Williams. Elementary Business Statistics: The Modern Approach. 2nd ed. Prentice-Hall, 1972.
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