Freund, J. E., Perles, B. M., & Williams, F. J. (1969). Freund and Williams' Modern business statistics. Prentice-Hall.
Cita Chicago (17th ed.)Freund, John E., Benjamin M. Perles, i Frank Jefferson Williams. Freund and Williams' Modern Business Statistics. Englewood Cliffs, N.J: Prentice-Hall, 1969.
Cita MLA (9th ed.)Freund, John E., et al. Freund and Williams' Modern Business Statistics. Prentice-Hall, 1969.
Atenció: Aquestes cites poden no estar 100% correctes.