Gregory, A., Hartley, J., & Lewis, D. (1969). Basic statistics. Methuen.
Lua i Stíl Chicago (17ú heag.)Gregory, A.H, J.R Hartley, agus D.G Lewis. Basic Statistics. London: Methuen, 1969.
Lua MLA (9ú heag.)Gregory, A.H, et al. Basic Statistics. Methuen, 1969.
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