Freund, J. E., & Williams, F. J. (1958). Modern business statistics. Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Freund, John E., agus Frank Jefferson Williams. Modern Business Statistics. Englewood Cliffs, N. J: Prentice-Hall, 1958.
Lua MLA (9ú heag.)Freund, John E., agus Frank Jefferson Williams. Modern Business Statistics. Prentice-Hall, 1958.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.