Siegel, I. H. (1968). Aggregation and averaging. W.E. Upjohn Institute for Employment Research.
Chicago-viite (17. p.)Siegel, Irving Herbert. Aggregation and Averaging. Michigan: W.E. Upjohn Institute for Employment Research, 1968.
MLA-viite (9. p.)Siegel, Irving Herbert. Aggregation and Averaging. W.E. Upjohn Institute for Employment Research, 1968.
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