Freedman, D., Pisani, R., & Purves, R. (1980). Statistics. Norton.
Lua i Stíl Chicago (17ú heag.)Freedman, David, Robert Pisani, agus Roger Purves. Statistics. New York: Norton, 1980.
Lua MLA (9ú heag.)Freedman, David, et al. Statistics. Norton, 1980.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.