ELDERtON , W. i. P. a. J. l., & ELDERTON, W. P. a. J. l. (1969). Systems of Frequency Curves. C.U. Press.
Chicago-čujuhus (17. p.)ELDERtON , W illiam Plain and JOHNSON,Norman lloyd, juo William Plain and JOHNSOn,Norman lloyd ELDERTON. Systems of Frequency Curves. Cambridge: C.U. Press, 1969.
MLA-čujuhus (9. p.)ELDERtON , W illiam Plain and JOHNSON,Norman lloyd, juo William Plain and JOHNSOn,Norman lloyd ELDERTON. Systems of Frequency Curves. C.U. Press, 1969.
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