00274nam a2200109Ia 450000500170000000800410001708200150005810000190007324500240009226000400011630000080015620260224041009.0260224s9999||||xx |||||||||||||| ||und||  a519.93 COC  aCochran, W.G.  0aSampling techniques  aNew York: John Wiley & Sons. c1977  a428